INSPECTING ARCHIVED INTELLIGENCE (OUTDATED VERSION).

Microsoft Defender ShieldBreak Zero-Day Vulnerability Patch

| 2026-08-17 09:05 CRITICAL HIGH EXPLOITED VULNERABILITY VULNERABILITY DISCLOSURE
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Executive Summary
AI-generated
The latest incident data reveals a critical vulnerability in Microsoft Defender, dubbed ShieldBreak. This zero-day exploit allows local attackers with limited permissions to gain SYSTEM privileges on fully patched Windows 10 and Windows 11 systems. The vulnerability was disclosed by Nightmare Eclipse, a security researcher who has previously exposed multiple zero-day exploits targeting Microsoft products. Microsoft has failed to properly patch the RoguePlanet vulnerability CVE-2026-50656, which also demonstrates a full patch bypass for ShieldBreak. The company is aware of the reported vulnerability and is actively investigating its validity and potential applicability.
Technical Mitigations AI-generated
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mp•••••.dll
un•••••.sys
Intelligence Metadata
Actors / Malware / CVEs / Campaigns
CVE-2026-72971CVE-2026-72971 CVE-2026-68820CVE-2026-68820 CVE-2026-69414CVE-2026-69414 CVE-2026-50656CVE-2026-50656 CVE-2026-62832CVE-2026-62832
Target & Sectors
NORTH_AMERICA NORTH_AMERICA
Incident Timeline
‎April 2026
Nightmare Eclipse disclosed multiple zero-day flaws in Microsoft Defender, BitLocker, and other Windows components since April 2026.
infrastructure Windows
Since April 2026, the researcher has disclosed LegacyHive , RoguePlanet , BlueHammer , RedSun , YellowKey , GreenPlasma , MiniPlasma , and UnDefend zero-day exploits targeting Microsoft Defender, BitLocker, and various other Windows components While Microsoft fixed the RoguePlanet vulnerability in July and the YellowKey, GreenPlasma, and MiniPlasma flaws as part of the June 2026 Patch Tuesday , the other vulnerabilities disclosed by Nightmare Eclipse are still waiting for an official patch.
Nightmare Eclipse has disclosed multiple zero-day flaws since April 2026, including ShieldBreak , LegacyHive , RoguePlanet , YellowKey , BlueHammer , RedSun , GreenPlasma , MiniPlasma , and UnDefend in Microsoft Defender, BitLocker, and other Windows components.
organisation BitLocker
Since April 2026, the researcher has disclosed LegacyHive , RoguePlanet , BlueHammer , RedSun , YellowKey , GreenPlasma , MiniPlasma , and UnDefend zero-day exploits targeting Microsoft Defender, BitLocker, and various other Windows components While Microsoft fixed the RoguePlanet vulnerability in July and the YellowKey, GreenPlasma, and MiniPlasma flaws as part of the June 2026 Patch Tuesday , the other vulnerabilities disclosed by Nightmare Eclipse are still waiting for an official patch.
Nightmare Eclipse has disclosed multiple zero-day flaws since April 2026, including ShieldBreak , LegacyHive , RoguePlanet , YellowKey , BlueHammer , RedSun , GreenPlasma , MiniPlasma , and UnDefend in Microsoft Defender, BitLocker, and other Windows components.
organisation BlueHammer
Since April 2026, the researcher has disclosed LegacyHive , RoguePlanet , BlueHammer , RedSun , YellowKey , GreenPlasma , MiniPlasma , and UnDefend zero-day exploits targeting Microsoft Defender, BitLocker, and various other Windows components While Microsoft fixed the RoguePlanet vulnerability in July and the YellowKey, GreenPlasma, and MiniPlasma flaws as part of the June 2026 Patch Tuesday , the other vulnerabilities disclosed by Nightmare Eclipse are still waiting for an official patch.
Nightmare Eclipse has disclosed multiple zero-day flaws since April 2026, including ShieldBreak , LegacyHive , RoguePlanet , YellowKey , BlueHammer , RedSun , GreenPlasma , MiniPlasma , and UnDefend in Microsoft Defender, BitLocker, and other Windows components.
organisation YellowKey
Since April 2026, the researcher has disclosed LegacyHive , RoguePlanet , BlueHammer , RedSun , YellowKey , GreenPlasma , MiniPlasma , and UnDefend zero-day exploits targeting Microsoft Defender, BitLocker, and various other Windows components While Microsoft fixed the RoguePlanet vulnerability in July and the YellowKey, GreenPlasma, and MiniPlasma flaws as part of the June 2026 Patch Tuesday , the other vulnerabilities disclosed by Nightmare Eclipse are still waiting for an official patch.
Nightmare Eclipse has disclosed multiple zero-day flaws since April 2026, including ShieldBreak , LegacyHive , RoguePlanet , YellowKey , BlueHammer , RedSun , GreenPlasma , MiniPlasma , and UnDefend in Microsoft Defender, BitLocker, and other Windows components.
organisation GreenPlasma
Since April 2026, the researcher has disclosed LegacyHive , RoguePlanet , BlueHammer , RedSun , YellowKey , GreenPlasma , MiniPlasma , and UnDefend zero-day exploits targeting Microsoft Defender, BitLocker, and various other Windows components While Microsoft fixed the RoguePlanet vulnerability in July and the YellowKey, GreenPlasma, and MiniPlasma flaws as part of the June 2026 Patch Tuesday , the other vulnerabilities disclosed by Nightmare Eclipse are still waiting for an official patch.
Nightmare Eclipse has disclosed multiple zero-day flaws since April 2026, including ShieldBreak , LegacyHive , RoguePlanet , YellowKey , BlueHammer , RedSun , GreenPlasma , MiniPlasma , and UnDefend in Microsoft Defender, BitLocker, and other Windows components.
organisation MiniPlasma
Since April 2026, the researcher has disclosed LegacyHive , RoguePlanet , BlueHammer , RedSun , YellowKey , GreenPlasma , MiniPlasma , and UnDefend zero-day exploits targeting Microsoft Defender, BitLocker, and various other Windows components While Microsoft fixed the RoguePlanet vulnerability in July and the YellowKey, GreenPlasma, and MiniPlasma flaws as part of the June 2026 Patch Tuesday , the other vulnerabilities disclosed by Nightmare Eclipse are still waiting for an official patch.
organisation Microsoft Defender
Nightmare Eclipse has disclosed multiple zero-day flaws since April 2026, including ShieldBreak , LegacyHive , RoguePlanet , YellowKey , BlueHammer , RedSun , GreenPlasma , MiniPlasma , and UnDefend in Microsoft Defender, BitLocker, and other Windows components.
organisation ShieldBreak
Nightmare Eclipse has disclosed multiple zero-day flaws since April 2026, including ShieldBreak , LegacyHive , RoguePlanet , YellowKey , BlueHammer , RedSun , GreenPlasma , MiniPlasma , and UnDefend in Microsoft Defender, BitLocker, and other Windows components.
‎June 2026
Threat actors used Microsoft's YellowKey exploit to target Windows systems.
organisation MiniPlasma
While the company fixed the YellowKey, GreenPlasma, and MiniPlasma flaws as part of the June 2026 Patch Tuesday and RoguePlanet in July , the other security flaws disclosed by Nightmare Eclipse remain zero-days and are still awaiting an official patch.
Microsoft patched the YellowKey, GreenPlasma, and MiniPlasma flaws as part of the June 2026 Patch Tuesday, and the RoguePlanet vulnerability in July , but the other zero-days are still awaiting an official patch.
Since April 2026, the researcher has disclosed LegacyHive , RoguePlanet , BlueHammer , RedSun , YellowKey , GreenPlasma , MiniPlasma , and UnDefend zero-day exploits targeting Microsoft Defender, BitLocker, and various other Windows components While Microsoft fixed the RoguePlanet vulnerability in July and the YellowKey, GreenPlasma, and MiniPlasma flaws as part of the June 2026 Patch Tuesday , the other vulnerabilities disclosed by Nightmare Eclipse are still waiting for an official patch.
organisation RoguePlanet
Microsoft patched the YellowKey, GreenPlasma, and MiniPlasma flaws as part of the June 2026 Patch Tuesday, and the RoguePlanet vulnerability in July , but the other zero-days are still awaiting an official patch.
infrastructure Windows
Since April 2026, the researcher has disclosed LegacyHive , RoguePlanet , BlueHammer , RedSun , YellowKey , GreenPlasma , MiniPlasma , and UnDefend zero-day exploits targeting Microsoft Defender, BitLocker, and various other Windows components While Microsoft fixed the RoguePlanet vulnerability in July and the YellowKey, GreenPlasma, and MiniPlasma flaws as part of the June 2026 Patch Tuesday , the other vulnerabilities disclosed by Nightmare Eclipse are still waiting for an official patch.
The exploit was successfully tested on fully updated Windows 10 and Windows 11 systems running the  June 2026 Patch Tuesday  updates, showing that patched systems may still be vulnerable.
organisation BitLocker
Since April 2026, the researcher has disclosed LegacyHive , RoguePlanet , BlueHammer , RedSun , YellowKey , GreenPlasma , MiniPlasma , and UnDefend zero-day exploits targeting Microsoft Defender, BitLocker, and various other Windows components While Microsoft fixed the RoguePlanet vulnerability in July and the YellowKey, GreenPlasma, and MiniPlasma flaws as part of the June 2026 Patch Tuesday , the other vulnerabilities disclosed by Nightmare Eclipse are still waiting for an official patch.
organisation BlueHammer
Since April 2026, the researcher has disclosed LegacyHive , RoguePlanet , BlueHammer , RedSun , YellowKey , GreenPlasma , MiniPlasma , and UnDefend zero-day exploits targeting Microsoft Defender, BitLocker, and various other Windows components While Microsoft fixed the RoguePlanet vulnerability in July and the YellowKey, GreenPlasma, and MiniPlasma flaws as part of the June 2026 Patch Tuesday , the other vulnerabilities disclosed by Nightmare Eclipse are still waiting for an official patch.
organisation YellowKey
Since April 2026, the researcher has disclosed LegacyHive , RoguePlanet , BlueHammer , RedSun , YellowKey , GreenPlasma , MiniPlasma , and UnDefend zero-day exploits targeting Microsoft Defender, BitLocker, and various other Windows components While Microsoft fixed the RoguePlanet vulnerability in July and the YellowKey, GreenPlasma, and MiniPlasma flaws as part of the June 2026 Patch Tuesday , the other vulnerabilities disclosed by Nightmare Eclipse are still waiting for an official patch.
organisation GreenPlasma
Since April 2026, the researcher has disclosed LegacyHive , RoguePlanet , BlueHammer , RedSun , YellowKey , GreenPlasma , MiniPlasma , and UnDefend zero-day exploits targeting Microsoft Defender, BitLocker, and various other Windows components While Microsoft fixed the RoguePlanet vulnerability in July and the YellowKey, GreenPlasma, and MiniPlasma flaws as part of the June 2026 Patch Tuesday , the other vulnerabilities disclosed by Nightmare Eclipse are still waiting for an official patch.
general_metric 10 patched Windows
The exploit was successfully tested on fully updated Windows 10 and Windows 11 systems running the  June 2026 Patch Tuesday  updates, showing that patched systems may still be vulnerable.
general_metric 11 Windows
The exploit was successfully tested on fully updated Windows 10 and Windows 11 systems running the  June 2026 Patch Tuesday  updates, showing that patched systems may still be vulnerable.
‎2026/07/13
Microsoft patches LegacyHive Zero-Day Vulnerability using CVE-2026-62832.
tactic Privilege Escalation
One of the patches involves CVE-2026-62832 (CVSS score: 7.8), a Windows User Profile Service privilege escalation vulnerability that was disclosed by Chaotic Eclipse last month under the name LegacyHive .
infrastructure Windows
One of the patches involves CVE-2026-62832 (CVSS score: 7.8), a Windows User Profile Service privilege escalation vulnerability that was disclosed by Chaotic Eclipse last month under the name LegacyHive .
vulnerability CVE-2026-62832
One of the patches involves CVE-2026-62832 (CVSS score: 7.8), a Windows User Profile Service privilege escalation vulnerability that was disclosed by Chaotic Eclipse last month under the name LegacyHive .
organisation Windows User Profile Service
One of the patches involves CVE-2026-62832 (CVSS score: 7.8), a Windows User Profile Service privilege escalation vulnerability that was disclosed by Chaotic Eclipse last month under the name LegacyHive .
general_metric 7.8 score
One of the patches involves CVE-2026-62832 (CVSS score: 7.8), a Windows User Profile Service privilege escalation vulnerability that was disclosed by Chaotic Eclipse last month under the name LegacyHive .
‎July 2026
Nightmare Eclipse published a proof-of-concept exploit for the Windows User Profile Service vulnerability known as LegacyHive.
infrastructure Windows
Microsoft has released security patches to address a Windows zero-day vulnerability known as "LegacyHive," disclosed after the July 2026 Patch Tuesday.
Nightmare Eclipse published a LegacyHive proof-of-concept (PoC) exploit hours after the July 2026 Patch Tuesday security updates were released, claiming it exploits a security vulnerability in the Windows User Profile Service.
In July, just hours after  Microsoft’s July 2026 Patch Tuesday ,  Chaotic Eclipse , published a new Windows zero-day proof-of-concept called LegacyHive.
organisation Nightmare
Nightmare Eclipse published a LegacyHive proof-of-concept (PoC) exploit hours after the July 2026 Patch Tuesday security updates were released, claiming it exploits a security vulnerability in the Windows User Profile Service.
organisation PoC
Nightmare Eclipse published a LegacyHive proof-of-concept (PoC) exploit hours after the July 2026 Patch Tuesday security updates were released, claiming it exploits a security vulnerability in the Windows User Profile Service.
organisation the Windows User Profile Service
Nightmare Eclipse published a LegacyHive proof-of-concept (PoC) exploit hours after the July 2026 Patch Tuesday security updates were released, claiming it exploits a security vulnerability in the Windows User Profile Service.
organisation LegacyHive
In July, just hours after  Microsoft’s July 2026 Patch Tuesday ,  Chaotic Eclipse , published a new Windows zero-day proof-of-concept called LegacyHive.
‎July 20
Threat actors used Microsoft's 0Patch platform to release free unofficial LegacyHive patches for systems running Windows 10 2004 or later and Windows Server 2022 or later.
infrastructure Windows
" ACROS Security, the company behind the 0Patch cybersecurity platform, also released free unofficial LegacyHive patches on July 20 for systems running Windows 10 2004 or later and Windows Server 2022 or later.
tactic T1584.004 - Server
" ACROS Security, the company behind the 0Patch cybersecurity platform, also released free unofficial LegacyHive patches on July 20 for systems running Windows 10 2004 or later and Windows Server 2022 or later.
general_metric 10 patched Windows
" ACROS Security, the company behind the 0Patch cybersecurity platform, also released free unofficial LegacyHive patches on July 20 for systems running Windows 10 2004 or later and Windows Server 2022 or later.
organisation ACROS Security
" ACROS Security, the company behind the 0Patch cybersecurity platform, also released free unofficial LegacyHive patches on July 20 for systems running Windows 10 2004 or later and Windows Server 2022 or later.
‎2026/08/10
Microsoft patched the LegacyHive zero-day vulnerability using ShieldBreak exploit.
organisation Vulnerability
" Vulnerability analyst Will Dormann confirmed last week that the ShieldBreak exploit works but added that Microsoft Defender must also be enabled for attackers to escalate privileges.
organisation Microsoft Defender
" Vulnerability analyst Will Dormann confirmed last week that the ShieldBreak exploit works but added that Microsoft Defender must also be enabled for attackers to escalate privileges.
‎Aug 12, 2026
Microsoft released a security update to patch the LegacyHive zero-day vulnerability.
‎2026/08/17
Microsoft has failed to properly patch the RoguePlanet vulnerability CVE-2026-50656, this PoC demonstrates a full patch bypass.
infrastructure Windows
" Nightmare Eclipse described ShieldBreak as a bypass for RoguePlanet , another Defender privilege escalation flaw disclosed in June, and shared a ShieldBreak proof-of-concept (PoC) exploit that local attackers with limited permissions can use to gain SYSTEM privileges on fully patched Windows 10, Windows 11, and Windows Server systems.
"The PoC was tested in the latest version of windows 11 25h2 (+Canary channel) and windows server 2025, the PoC also have a 100% success rate.
Please note that Windows 10 (and respective server editions) are not currently supported, they are however vulnerable to ShieldBreak as well.
Since April, Nightmare Eclipse has disclosed multiple zero-day exploits targeting Microsoft Defender, BitLocker, and various other Windows components, now known as LegacyHive , RoguePlanet , BlueHammer , RedSun , YellowKey , GreenPlasma , MiniPlasma , and UnDefend .
Microsoft patches LegacyHive Windows zero-day vulnerability.
The company says that LegacyHive stems from improper link resolution before file access ('link following') in the Windows User Profile Service, and successful exploitation allows local attackers to gain administrator privileges.
" According to Nightmare Eclipse, ShieldBreak can be used to gain SYSTEM privileges on fully patched Windows 10, Windows 11, and Windows Server systems.
ShieldBreak: New Windows Zero-Day Bypasses Microsoft’s RoguePlanet Patch.
ShieldBreak: New Windows Zero-Day Bypasses Microsoft’s RoguePlanet Patch Chaotic Eclipse released a PoC for ShieldBreak, a Microsoft Defender zero-day that bypasses the CVE-2026-50656 patch and could enable SYSTEM-level code execution.
Successful exploitation could enable arbitrary code execution and other unauthorized actions on affected Windows systems.
“The PoC was tested in the latest version of windows 11 25h2 (+Canary channel) and windows server 2025, the PoC also have a 100% success rate.
Please note that Windows 10 (and respective server editions) are not currently supported, they are however vulnerable to ShieldBreak as well.”
The researcher tested the PoC on Windows 11 25H2 and Windows Server 2025 with a 100% success rate.
Windows 10 is also vulnerable, though not currently supported by the PoC. In May, the researcher disclosed two other  Windows zero-day vulnerabilities  named  YellowKey  and  GreenPlasma .
The flaws affect BitLocker and the Windows Collaborative Translation Framework (CTFMON).
This time, the target is the Windows User Profile Service (ProfSvc), and unlike the hundreds of vulnerabilities Microsoft fixed this month, this one currently has no CVE, no advisory, and no security update.
Soon after, Chaotic Eclipse said the "defense-in-depth updates" introduced by Microsoft to address CVE-2026-50656 can cause Defender to leak 8 bytes of data when attempting to open a file in certain scenarios on Windows 11 25H2 and Windows Server 2025.
The vulnerability, rooted in Microsoft Defender for Windows, demonstrates a patch bypass for CVE-2026-50656 (CVSS score: 7.8), otherwise known as RoguePlanet .
ShieldBreak, on the other hand, is assessed to be a full patch bypass for CVE-2026-50656, with the researcher claiming that "Microsoft has failed to properly patch the RoguePlanet vulnerability." "The PoC was tested in the latest version of Windows 11 25h2 (+Canary channel) and Windows Server 2025, the PoC also have a 100% success rate," the researcher added.
"Please note that Windows 10 (and respective server editions) are not currently supported, they are however vulnerable to ShieldBreak as well.
The development comes as the Windows maker shipped patches for 421 security flaws , including 236 flaws in Windows.
"Improper link resolution before file access ('link following') in Windows User Profile Service allows an authorized attacker to elevate privileges locally," Microsoft said.
" Also remediated by Microsoft is an actively exploited zero-day in the Windows Ancillary Function Driver for WinSock ( CVE-2026-68820 , CVSS score: 7.0) that grants SYSTEM privileges and a publicly disclosed Windows Container Isolation FS Filter Driver (unionfs.sys) tampering vulnerability ( CVE-2026-72971 , CVSS score: 5.5).
organisation Nightmare
" Nightmare Eclipse described ShieldBreak as a bypass for RoguePlanet , another Defender privilege escalation flaw disclosed in June, and shared a ShieldBreak proof-of-concept (PoC) exploit that local attackers with limited permissions can use to gain SYSTEM privileges on fully patched Windows 10, Windows 11, and Windows Server systems.
Security researcher Chaotic Eclipse , also known as INFINITE NIGHTMARE, MSNightmare and Nightmare-Eclipse, released a PoC for ShieldBreak, a Microsoft Defender zero-day.
 Ravie Lakshmanan  Aug 12, 2026 Zero-Day / Vulnerability The security researcher going by the name Chaotic Eclipse (aka INFINITE NIGHTMARE, MSNightmare, and Nightmare-Eclipse) has released a proof-of-concept (PoC) for a new Microsoft zero-day called ShieldBreak .
organisation PoC
" Nightmare Eclipse described ShieldBreak as a bypass for RoguePlanet , another Defender privilege escalation flaw disclosed in June, and shared a ShieldBreak proof-of-concept (PoC) exploit that local attackers with limited permissions can use to gain SYSTEM privileges on fully patched Windows 10, Windows 11, and Windows Server systems.
 Ravie Lakshmanan  Aug 12, 2026 Zero-Day / Vulnerability The security researcher going by the name Chaotic Eclipse (aka INFINITE NIGHTMARE, MSNightmare, and Nightmare-Eclipse) has released a proof-of-concept (PoC) for a new Microsoft zero-day called ShieldBreak .
"Microsoft has failed to properly patch the RoguePlanet vulnerability CVE-2026-50656, this PoC demonstrates a full patch bypass," they said .
“Microsoft has failed to properly patch the RoguePlanet vulnerability CVE-2026-50656, this PoC demonstrates a full patch bypass.” said Chaotic Eclipse .
organisation YellowKey
YellowKey could allow attackers to bypass BitLocker protections, while GreenPlasma enables privilege escalation.
Since April, Nightmare Eclipse has disclosed multiple zero-day exploits targeting Microsoft Defender, BitLocker, and various other Windows components, now known as LegacyHive , RoguePlanet , BlueHammer , RedSun , YellowKey , GreenPlasma , MiniPlasma , and UnDefend .
organisation the Microsoft
The tech giant described it as a privilege escalation issue in the Microsoft Malware Protection Engine ("mpengine.dll").
"Microsoft is aware of an elevation of privilege in the Microsoft Malware Protection Engine in Microsoft Defender publicly referred to as 'ShieldBreak,'" the company said.
The Microsoft Malware Protection Engine (mpengine.dll) powers Defender’s malware scanning, detection, and removal functions.
organisation BitLocker
Since April, Nightmare Eclipse has disclosed multiple zero-day exploits targeting Microsoft Defender, BitLocker, and various other Windows components, now known as LegacyHive , RoguePlanet , BlueHammer , RedSun , YellowKey , GreenPlasma , MiniPlasma , and UnDefend .
The flaws affect BitLocker and the Windows Collaborative Translation Framework (CTFMON).
organisation BlueHammer
Since April, Nightmare Eclipse has disclosed multiple zero-day exploits targeting Microsoft Defender, BitLocker, and various other Windows components, now known as LegacyHive , RoguePlanet , BlueHammer , RedSun , YellowKey , GreenPlasma , MiniPlasma , and UnDefend .
“The vulnerabilities known as  RedSun ,  UnDefend ,  BlueHammer ,  YellowKey , GreenPlasma, and MiniPlasma were not responsibly disclosed.”
organisation GreenPlasma
Since April, Nightmare Eclipse has disclosed multiple zero-day exploits targeting Microsoft Defender, BitLocker, and various other Windows components, now known as LegacyHive , RoguePlanet , BlueHammer , RedSun , YellowKey , GreenPlasma , MiniPlasma , and UnDefend .
Windows 10 is also vulnerable, though not currently supported by the PoC. In May, the researcher disclosed two other  Windows zero-day vulnerabilities  named  YellowKey  and  GreenPlasma .
organisation Microsoft
Microsoft patches LegacyHive Windows zero-day vulnerability.
ShieldBreak: New Windows Zero-Day Bypasses Microsoft’s RoguePlanet Patch.
Microsoft working on Defender patch for ShieldBreak zero-day.
ShieldBreak Zero-Day PoC Claims Microsoft Defender Patch Bypass With SYSTEM Access.
organisation ShieldBreak
ShieldBreak: New Windows Zero-Day Bypasses Microsoft’s RoguePlanet Patch.
 Ravie Lakshmanan  Aug 12, 2026 Zero-Day / Vulnerability The security researcher going by the name Chaotic Eclipse (aka INFINITE NIGHTMARE, MSNightmare, and Nightmare-Eclipse) has released a proof-of-concept (PoC) for a new Microsoft zero-day called ShieldBreak .
​"Microsoft is aware of the reported vulnerability and is actively investigating the validity and potential applicability of these claims," a Microsoft spokesperson told BleepingComputer when asked for a statement regarding the new ShieldBreak zero-day.
New Microsoft Defender 'ShieldBreak' zero-day grants SYSTEM privileges.
organisation the Windows Collaborative Translation Framework
The flaws affect BitLocker and the Windows Collaborative Translation Framework (CTFMON).
organisation CTFMON
The flaws affect BitLocker and the Windows Collaborative Translation Framework (CTFMON).
organisation the Windows User Profile Service
This time, the target is the Windows User Profile Service (ProfSvc), and unlike the hundreds of vulnerabilities Microsoft fixed this month, this one currently has no CVE, no advisory, and no security update.
organisation ProfSvc
This time, the target is the Windows User Profile Service (ProfSvc), and unlike the hundreds of vulnerabilities Microsoft fixed this month, this one currently has no CVE, no advisory, and no security update.
data_breach 8 bytes
Soon after, Chaotic Eclipse said the "defense-in-depth updates" introduced by Microsoft to address CVE-2026-50656 can cause Defender to leak 8 bytes of data when attempting to open a file in certain scenarios on Windows 11 25H2 and Windows Server 2025.
Now Chaotic Eclipse claims ShieldBreak fully bypasses Microsoft’s CVE-2026-50656 patch, while Defender may also leak 8 bytes of data under certain conditions.
organisation CVE-2026
Soon after, Chaotic Eclipse said the "defense-in-depth updates" introduced by Microsoft to address CVE-2026-50656 can cause Defender to leak 8 bytes of data when attempting to open a file in certain scenarios on Windows 11 25H2 and Windows Server 2025.
organisation Microsoft Defender
The vulnerability, rooted in Microsoft Defender for Windows, demonstrates a patch bypass for CVE-2026-50656 (CVSS score: 7.8), otherwise known as RoguePlanet .
" Will Dormann, principal vulnerability analyst at Tharros, confirmed on Tuesday that the exploit works , saying that Microsoft Defender needs to be enabled for the ShieldBreak exploit to escalate attackers' privileges.
In mid-June, Microsoft acknowledged the RoguePlanet zero-day affecting Microsoft Defender and stated it is aware of the issue and was actively developing a security update to address the flaw and protect affected systems.
organisation CVSS
" Also remediated by Microsoft is an actively exploited zero-day in the Windows Ancillary Function Driver for WinSock ( CVE-2026-68820 , CVSS score: 7.0) that grants SYSTEM privileges and a publicly disclosed Windows Container Isolation FS Filter Driver (unionfs.sys) tampering vulnerability ( CVE-2026-72971 , CVSS score: 5.5).
In early July, Microsoft released security updates for  RoguePlanet , a vulnerability tracked as  CVE-2026-50656  (CVSS score of 7.8) affecting the Malware Protection Engine used by Defender.
organisation the Windows Ancillary Function
" Also remediated by Microsoft is an actively exploited zero-day in the Windows Ancillary Function Driver for WinSock ( CVE-2026-68820 , CVSS score: 7.0) that grants SYSTEM privileges and a publicly disclosed Windows Container Isolation FS Filter Driver (unionfs.sys) tampering vulnerability ( CVE-2026-72971 , CVSS score: 5.5).
organisation Windows Container Isolation FS Filter
" Also remediated by Microsoft is an actively exploited zero-day in the Windows Ancillary Function Driver for WinSock ( CVE-2026-68820 , CVSS score: 7.0) that grants SYSTEM privileges and a publicly disclosed Windows Container Isolation FS Filter Driver (unionfs.sys) tampering vulnerability ( CVE-2026-72971 , CVSS score: 5.5).
organisation INFINITE NIGHTMARE
Security researcher Chaotic Eclipse , also known as INFINITE NIGHTMARE, MSNightmare and Nightmare-Eclipse, released a PoC for ShieldBreak, a Microsoft Defender zero-day.
 Ravie Lakshmanan  Aug 12, 2026 Zero-Day / Vulnerability The security researcher going by the name Chaotic Eclipse (aka INFINITE NIGHTMARE, MSNightmare, and Nightmare-Eclipse) has released a proof-of-concept (PoC) for a new Microsoft zero-day called ShieldBreak .
organisation MSNightmare
Security researcher Chaotic Eclipse , also known as INFINITE NIGHTMARE, MSNightmare and Nightmare-Eclipse, released a PoC for ShieldBreak, a Microsoft Defender zero-day.
 Ravie Lakshmanan  Aug 12, 2026 Zero-Day / Vulnerability The security researcher going by the name Chaotic Eclipse (aka INFINITE NIGHTMARE, MSNightmare, and Nightmare-Eclipse) has released a proof-of-concept (PoC) for a new Microsoft zero-day called ShieldBreak .
organisation Chaotic Eclipse
 Ravie Lakshmanan  Aug 12, 2026 Zero-Day / Vulnerability The security researcher going by the name Chaotic Eclipse (aka INFINITE NIGHTMARE, MSNightmare, and Nightmare-Eclipse) has released a proof-of-concept (PoC) for a new Microsoft zero-day called ShieldBreak .
organisation RoguePlanet
“Microsoft has failed to properly patch the RoguePlanet vulnerability CVE-2026-50656, this PoC demonstrates a full patch bypass.” said Chaotic Eclipse .
"Microsoft has failed to properly patch the RoguePlanet vulnerability CVE-2026-50656, this PoC demonstrates a full patch bypass," Nightmare Eclipse said .
"RoguePlanet was a filesystem race condition vuln that uses virtual disks and NT native file manipulation to trick quarantine process into overwriting system files," Beaumont noted .
RoguePlanet has been described as a race condition that, if successfully exploited, could grant an attacker the ability to spawn a shell with SYSTEM-level privileges, enabling them to run arbitrary code or perform unauthorized actions.
infrastructure 7.8
In early July, Microsoft released security updates for  RoguePlanet , a vulnerability tracked as  CVE-2026-50656  (CVSS score of 7.8) affecting the Malware Protection Engine used by Defender.
organisation Vulnerability
"Microsoft is aware of the reported vulnerability and is actively investigating the validity and potential applicability of these claims," a Microsoft spokesperson told BleepingComputer when asked for a statement regarding LegacyHive. Vulnerability analyst Will Dormann explained that non-admin users can use Nightmare Eclipse's exploit to modify the classes registry hive and gain automatic code execution when the admin account logs in to a compromised system.
organisation BleepingComputer
"Microsoft is aware of the reported vulnerability and is actively investigating the validity and potential applicability of these claims," a Microsoft spokesperson told BleepingComputer when asked for a statement regarding LegacyHive. Vulnerability analyst Will Dormann explained that non-admin users can use Nightmare Eclipse's exploit to modify the classes registry hive and gain automatic code execution when the admin account logs in to a compromised system.
​"Microsoft is aware of the reported vulnerability and is actively investigating the validity and potential applicability of these claims," a Microsoft spokesperson told BleepingComputer when asked for a statement regarding the new ShieldBreak zero-day.
BleepingComputer has contacted a Microsoft spokesperson about the new ShieldBreak zero-day and will update the story if we receive a statement.
organisation LegacyHive
"Microsoft is aware of the reported vulnerability and is actively investigating the validity and potential applicability of these claims," a Microsoft spokesperson told BleepingComputer when asked for a statement regarding LegacyHive. Vulnerability analyst Will Dormann explained that non-admin users can use Nightmare Eclipse's exploit to modify the classes registry hive and gain automatic code execution when the admin account logs in to a compromised system.
organisation Tharros
" Will Dormann, principal vulnerability analyst at Tharros, confirmed on Tuesday that the exploit works , saying that Microsoft Defender needs to be enabled for the ShieldBreak exploit to escalate attackers' privileges.
organisation ShieldBreak PoC
ShieldBreak PoC exploit demo (Nightmare Eclipse) Tracked as CVE-2026-69414 and waiting for a patch On Friday, three days after ShieldBreak was disclosed, Microsoft said it's now tracking the flaw as CVE-2026-69414 and confirmed it's working on a patch, but has yet to acknowledge that Nightmare Eclipse found it.
ShieldBreak PoC exploit demo (Nightmare Eclipse)
organisation MiniPlasma
“The vulnerabilities known as  RedSun ,  UnDefend ,  BlueHammer ,  YellowKey , GreenPlasma, and MiniPlasma were not responsibly disclosed.”
organisation ShieldBreak Zero-Day
ShieldBreak Zero-Day PoC Claims Microsoft Defender Patch Bypass With SYSTEM Access.
organisation "Microsoft
​"Microsoft is aware of the reported vulnerability and is actively investigating the validity and potential applicability of these claims," a Microsoft spokesperson told BleepingComputer when asked for a statement regarding the new ShieldBreak zero-day.
organisation The Blue Report 2026
The Blue Report 2026 measures defenses technique by technique across 338 million simulations run in customer production environments.
organisation Microsoft Defender for Endpoint
One day after the PoC was released, cybersecurity expert Kevin Beaumont also published LegacyHive exploitation detection queries for Microsoft Defender for Endpoint (MDE) and  confirmed that the exploit worked .
However, cybersecurity expert Kevin Beaumont, who also  published ShieldBreak exploitation detection queries  for Microsoft Defender for Endpoint,  said  that the two exploits work very differently.
organisation MDE
One day after the PoC was released, cybersecurity expert Kevin Beaumont also published LegacyHive exploitation detection queries for Microsoft Defender for Endpoint (MDE) and  confirmed that the exploit worked .
organisation Coordinated Vulnerability Disclosure
Microsoft’s post is essentially a public defense of Coordinated Vulnerability Disclosure, the standard practice where a researcher notifies a vendor privately, gives them time to fix the issue, and then goes public.
organisation MSRC
The researcher criticized Microsoft for revoking access to their MSRC account, rejecting reports, and failing to provide compensation.
organisation Microsoft’s Security Response Center
At the end of May, Microsoft’s Security Response Center  called  the zero-day dumps irresponsible.
organisation the User Profile Service
An attacker who already has code execution as a standard user can abuse the User Profile Service to load another user’s registry hive, potentially that of a local administrator, under their own profile.
organisation SecurityAffairs
Follow me on Twitter:  @securityaffairs  and  Facebook  and  Mastodon Pierluigi Paganini ( SecurityAffairs  – hacking,  ShieldBreak )
organisation The Hacker News
Microsoft told The Hacker News at the time that it's aware of the report and is investigating.
‎August 2026
Microsoft confirmed it has begun working on a security patch for the Defender zero-day vulnerability known as "ShieldBreak".
tactic Privilege Escalation
On Friday, Microsoft confirmed it has begun working on a security patch for a Defender zero-day vulnerability named "ShieldBreak." A security researcher who uses the "Nightmare Eclipse" handle disclosed this privilege escalation vulnerability after Microsoft released the August 2026 Patch Tuesday security updates.
organisation Nightmare
A security researcher known as Nightmare Eclipse has released a new Microsoft Defender zero-day exploit named " ShieldBreak " after Microsoft released the August 2026 Patch Tuesday security updates.
organisation Microsoft
A security researcher known as Nightmare Eclipse has released a new Microsoft Defender zero-day exploit named " ShieldBreak " after Microsoft released the August 2026 Patch Tuesday security updates.
‎August 25, 2026
Threat actors used Microsoft's LegacyHive zero-day vulnerability exploit to target the CVE-2026-68820 vulnerability.
vulnerability CVE-2026-68820
The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has since added CVE-2026-68820 to its Known Exploited Vulnerabilities ( KEV ) catalog, requiring federal agencies to apply the fixes by August 25, 2026.
attribution Known Exploited
The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has since added CVE-2026-68820 to its Known Exploited Vulnerabilities ( KEV ) catalog, requiring federal agencies to apply the fixes by August 25, 2026.
tactic T1588.006 - Vulnerabilities
The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has since added CVE-2026-68820 to its Known Exploited Vulnerabilities ( KEV ) catalog, requiring federal agencies to apply the fixes by August 25, 2026.
attribution KEV
The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has since added CVE-2026-68820 to its Known Exploited Vulnerabilities ( KEV ) catalog, requiring federal agencies to apply the fixes by August 25, 2026.
Tactical Metrics
Metrics
infrastructure
‎Windows
Affected Product
…rivilege escalation flaw disclosed in June, and shared a ShieldBreak proof-of-concept (PoC) exploit that local attackers with limited permissions can use to gain SYSTEM privileges on fully patched Windows 10, Windows 11, and Windows Server systems.
"The PoC was tested in the latest version of windows 11 25h2 (+Canary channel) and windows server 2025, the PoC also have a 100% success rate.
Please note that Windows 10 (and respective server editions) are not currently supported, they are however vulnerable to ShieldBreak as well.
…pril, Nightmare Eclipse has disclosed multiple zero-day exploits targeting Microsoft Defender, BitLocker, and various other Windows components, now known as LegacyHive , RoguePlanet , BlueHammer , RedSun , YellowKey , GreenPlasma , MiniPlasm…
Microsoft patches LegacyHive Windows zero-day vulnerability.
Microsoft has released security patches to address a Windows zero-day vulnerability known as "LegacyHive," disclosed after the July 2026 Patch Tuesday.
Nightmare Eclipse published a LegacyHive proof-of-concept (PoC) exploit hours after the July 2026 Patch Tuesday security updates were released, claiming it exploits a security vulnerability in the Windows User Profile Service.
The company says that LegacyHive stems from improper link resolution before file access ('link following') in the Windows User Profile Service, and successful exploitation allows local attackers to gain administrator privileges.
" ACROS Security, the company behind the 0Patch cybersecurity platform, also released free unofficial LegacyHive patches on July 20 for systems running Windows 10 2004 or later and Windows Server 2022 or later.
…sclosed multiple zero-day flaws since April 2026, including ShieldBreak , LegacyHive , RoguePlanet , YellowKey , BlueHammer , RedSun , GreenPlasma , MiniPlasma , and UnDefend in Microsoft Defender, BitLocker, and other Windows components.
" According to Nightmare Eclipse, ShieldBreak can be used to gain SYSTEM privileges on fully patched Windows 10, Windows 11, and Windows Server systems.
…, GreenPlasma , MiniPlasma , and UnDefend zero-day exploits targeting Microsoft Defender, BitLocker, and various other Windows components While Microsoft fixed the RoguePlanet vulnerability in July and the YellowKey, GreenPlasma, and MiniP…
ShieldBreak: New Windows Zero-Day Bypasses Microsoft’s RoguePlanet Patch.
ShieldBreak: New Windows Zero-Day Bypasses Microsoft’s RoguePlanet Patch Chaotic Eclipse released a PoC for ShieldBreak, a Microsoft Defender zero-day that bypasses the CVE-2026-50656 patch and could enable SYSTEM-level code execution.
Successful exploitation could enable arbitrary code execution and other unauthorized actions on affected Windows systems.
“The PoC was tested in the latest version of windows 11 25h2 (+Canary channel) and windows server 2025, the PoC also have a 100% success rate.
Please note that Windows 10 (and respective server editions) are not currently supported, they are however vulnerable to ShieldBreak as well.”
The exploit was successfully tested on fully updated Windows 10 and Windows 11 systems running the  June 2026 Patch Tuesday  updates, showing that patched systems may still be vulnerable.
The researcher tested the PoC on Windows 11 25H2 and Windows Server 2025 with a 100% success rate.
Windows 10 is also vulnerable, though not currently supported by the PoC. In May, the researcher disclosed two other  Windows zero-day vulnerabilities  named  YellowKey  and  GreenPlasma .
The flaws affect BitLocker and the Windows Collaborative Translation Framework (CTFMON).
In July, just hours after  Microsoft’s July 2026 Patch Tuesday ,  Chaotic Eclipse , published a new Windows zero-day proof-of-concept called LegacyHive.
This time, the target is the Windows User Profile Service (ProfSvc), and unlike the hundreds of vulnerabilities Microsoft fixed this month, this one currently has no CVE, no advisory, and no security update.
…after, Chaotic Eclipse said the "defense-in-depth updates" introduced by Microsoft to address CVE-2026-50656 can cause Defender to leak 8 bytes of data when attempting to open a file in certain scenarios on Windows 11 25H2 and Windows Server 2025.
One of the patches involves CVE-2026-62832 (CVSS score: 7.8), a Windows User Profile Service privilege escalation vulnerability that was disclosed by Chaotic Eclipse last month under the name LegacyHive .
The vulnerability, rooted in Microsoft Defender for Windows, demonstrates a patch bypass for CVE-2026-50656 (CVSS score: 7.8), otherwise known as RoguePlanet .
…ing that "Microsoft has failed to properly patch the RoguePlanet vulnerability." "The PoC was tested in the latest version of Windows 11 25h2 (+Canary channel) and Windows Server 2025, the PoC also have a 100% success rate," the researcher added.
"Please note that Windows 10 (and respective server editions) are not currently supported, they are however vulnerable to ShieldBreak as well.
The development comes as the Windows maker shipped patches for 421 security flaws , including 236 flaws in Windows.
"Improper link resolution before file access ('link following') in Windows User Profile Service allows an authorized attacker to elevate privileges locally," Microsoft said.
" Also remediated by Microsoft is an actively exploited zero-day in the Windows Ancillary Function Driver for WinSock ( CVE-2026-68820 , CVSS score: 7.0) that grants SYSTEM privileges and a publicly disclosed Windows Container Isolation FS Filter…
Metrics
infrastructure
‎7.8
Software Version
In early July, Microsoft released security updates for  RoguePlanet , a vulnerability tracked as  CVE-2026-50656  (CVSS score of 7.8) affecting the Malware Protection Engine used by Defender.
Metrics
data_breach
8
Bytes
Now Chaotic Eclipse claims ShieldBreak fully bypasses Microsoft’s CVE-2026-50656 patch, while Defender may also leak 8 bytes of data under certain conditions.
…after, Chaotic Eclipse said the "defense-in-depth updates" introduced by Microsoft to address CVE-2026-50656 can cause Defender to leak 8 bytes of data when attempting to open a file in certain scenarios on Windows 11 25H2 and Windows Server 2025.
Intelligence Sources
BleepingComputer 2026-08-13
Security Affairs 2026-08-12
The Hacker News 2026-08-12
BleepingComputer 2026-08-12
BleepingComputer 2026-08-17