INSPECTING ARCHIVED INTELLIGENCE (OUTDATED VERSION).

TONTOU CPU Exploits Spectre v2 Fixes to Leaks Linux Password

| 2026-08-06 18:03 CRITICAL LOW DATA BREACH
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Executive Summary
AI-generated
A new CPU attack, dubbed TONTOU, was discovered by researchers Daniël Trujillo and Mengjia Yan at the Black Hat USA security conference on August 6, 2026. The attackers can bypass Spectre v2 fixes and leak Linux password hashes using an Interrupt Injection attack that exploits a time-of-neutralization to time-of-use window in AMD and Intel processors. This allows unprivileged user programs to schedule timer interrupts during kernel execution, forcing the kernel to redirect its control flow and poison microarchitectural states within a post-neutralization window. The researchers tested this attack on an AMD Zen 2 host with Spectre v2 mitigations, successfully running through all stages of the TONTOU attack: neutralization, redirection, poisoning, and using poisoned branch predictors.
Technical Mitigations AI-generated
• Reset credentials and API keys that may have been exposed, and review access logs for the affected accounts or integrations.
Intelligence Metadata
Actors / Malware / CVEs / Campaigns
InceptionInception
Target & Sectors
NORTH_AMERICA NORTH_AMERICA
Incident Timeline
‎2026/08/06
Researchers Daniël Trujillo and Mengjia Yan demonstrated a TONTOU attack that bypasses Spectre v2 fixes, allowing arbitrary kernel memory leaks at 5.47 bytes/s accuracy on AMD Zen 2 systems running Linux version 6.14.0-37-generic with 16GB of RAM.
infrastructure Linux
New TONTOU CPU attack bypasses Spectre v2 fixes, leaks Linux password hashes.
Researchers found a way to bypass recent mitigations for Spectre v2 speculative execution side-channel attacks and developed an exploit to leak secrets from Linux machines.
Mengjia and Trujillo tested the attack starting from the assumption that an attacker can run arbitrary, unprivileged code on a Linux target machine to leak data from the kernel.
On an AMD Zen 2 system running Linux version 6.14.0-37-generic with 16GB of RAM, the researchers showed it could leak arbitrary kernel memory at a rate of 5.47 bytes/s and 91.97% accuracy, including the contents of /etc/shadow, which stores passwor…
AMD has published an advisory today noting that the interrupt inject issue "appears to be associated" with how implementation on Linux of the Safe RET mitigation against potential information disclosure attacks.
infrastructure 6.14.0-37
On an AMD Zen 2 system running Linux version 6.14.0-37-generic with 16GB of RAM, the researchers showed it could leak arbitrary kernel memory at a rate of 5.47 bytes/s and 91.97% accuracy, including the contents of /etc/shadow, which stores passwor…
infrastructure 5.47
…Zen 2 system running Linux version 6.14.0-37-generic with 16GB of RAM, the researchers showed it could leak arbitrary kernel memory at a rate of 5.47 bytes/s and 91.97% accuracy, including the contents of /etc/shadow, which stores password hashes.
infrastructure 91.97
…Zen 2 system running Linux version 6.14.0-37-generic with 16GB of RAM, the researchers showed it could leak arbitrary kernel memory at a rate of 5.47 bytes/s and 91.97% accuracy, including the contents of /etc/shadow, which stores password hashes.
data_breach 5.47 bytes
…Zen 2 system running Linux version 6.14.0-37-generic with 16GB of RAM, the researchers showed it could leak arbitrary kernel memory at a rate of 5.47 bytes/s and 91.97% accuracy, including the contents of /etc/shadow, which stores password hashes.
data_breach 16 GB
On an AMD Zen 2 system running Linux version 6.14.0-37-generic with 16GB of RAM, the researchers showed it could leak arbitrary kernel memory at a rate of 5.47 bytes/s and 91.97% accuracy, including the contents of /etc/shadow, which stores password…
threat_actor Inception
Because passive RSB pollution is less reliable, they combined interrupt injection with Inception , a previously disclosed attack that Daniël Trujillo helped develop.
infrastructure 2 host
On an AMD Zen 2 host with the latest Spectre v2 mitigations, the two researchers successfully ran through all the stages of a TONTOU attack: neutralization, redirection, poisoning, and the use of the poisoned branch predictors.
Tactical Metrics
Metrics
infrastructure
‎Linux
Affected Product
New TONTOU CPU attack bypasses Spectre v2 fixes, leaks Linux password hashes.
Researchers found a way to bypass recent mitigations for Spectre v2 speculative execution side-channel attacks and developed an exploit to leak secrets from Linux machines.
Mengjia and Trujillo tested the attack starting from the assumption that an attacker can run arbitrary, unprivileged code on a Linux target machine to leak data from the kernel.
On an AMD Zen 2 system running Linux version 6.14.0-37-generic with 16GB of RAM, the researchers showed it could leak arbitrary kernel memory at a rate of 5.47 bytes/s and 91.97% accuracy, including the contents of /etc/shadow, which stores passwor…
AMD has published an advisory today noting that the interrupt inject issue "appears to be associated" with how implementation on Linux of the Safe RET mitigation against potential information disclosure attacks.
Metrics
infrastructure
‎6.14.0-37
Software Version
On an AMD Zen 2 system running Linux version 6.14.0-37-generic with 16GB of RAM, the researchers showed it could leak arbitrary kernel memory at a rate of 5.47 bytes/s and 91.97% accuracy, including the contents of /etc/shadow, which stores passwor…
Metrics
infrastructure
‎5.47
Software Version
…Zen 2 system running Linux version 6.14.0-37-generic with 16GB of RAM, the researchers showed it could leak arbitrary kernel memory at a rate of 5.47 bytes/s and 91.97% accuracy, including the contents of /etc/shadow, which stores password hashes.
Metrics
infrastructure
‎91.97
Software Version
…Zen 2 system running Linux version 6.14.0-37-generic with 16GB of RAM, the researchers showed it could leak arbitrary kernel memory at a rate of 5.47 bytes/s and 91.97% accuracy, including the contents of /etc/shadow, which stores password hashes.
Metrics
data_breach
16
Gb
On an AMD Zen 2 system running Linux version 6.14.0-37-generic with 16GB of RAM, the researchers showed it could leak arbitrary kernel memory at a rate of 5.47 bytes/s and 91.97% accuracy, including the contents of /etc/shadow, which stores password…
Metrics
data_breach
5
Bytes
…Zen 2 system running Linux version 6.14.0-37-generic with 16GB of RAM, the researchers showed it could leak arbitrary kernel memory at a rate of 5.47 bytes/s and 91.97% accuracy, including the contents of /etc/shadow, which stores password hashes.
Metrics
infrastructure
2
Host
On an AMD Zen 2 host with the latest Spectre v2 mitigations, the two researchers successfully ran through all the stages of a TONTOU attack: neutralization, redirection, poisoning, and the use of the poisoned branch predictors.
Intelligence Sources
BleepingComputer 2026-08-06