CVE-2025-38352: Linux Kernel Time-of-Check Time-of-Use (TOCTOU) Race Condition Vulnerability

Vulnerability summary

CVE-2025-38352 is a high (CVSS 7.8) vulnerability in Linux Kernel. It is known to be exploited: CISA lists it, first on 04-09-2025. EPSS estimates a 1.36% chance of exploitation in the next 30 days, higher than 71.6% of scored vulnerabilities. 1 public exploit is recorded.

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Timeline

1. 22-07-2025
   PublishedVulnerability first disclosed.
2. 04-09-2025
   Added to CISA KEVExploitedLinux Kernel Time-of-Check Time-of-Use (TOCTOU) Race Condition Vulnerability
3. 25-09-2025
   CISA remediation dueDeadline passedApply mitigations per vendor instructions.
4. 08-09-2026
   Last modifiedVulnerability information updated.

Description

In the Linux kernel, the following vulnerability has been resolved: posix-cpu-timers: fix race between handle_posix_cpu_timers() and posix_cpu_timer_del() If an exiting non-autoreaping task has already passed exit_notify() and calls handle_posix_cpu_timers() from IRQ, it can be reaped by its parent or debugger right after unlock_task_sighand(). If a concurrent posix_cpu_timer_del() runs at that moment, it won't be able to detect timer->it.cpu.firing != 0: cpu_timer_task_rcu() and/or lock_task_sighand() will fail. Add the tsk->exit_state check into run_posix_cpu_timers() to fix this. This fix is not needed if CONFIG_POSIX_CPU_TIMERS_TASK_WORK=y, because exit_task_work() is called before exit_notify(). But the check still makes sense, task_work_add(&tsk->posix_cputimers_work.work) will fail anyway in this case.

• CWE-367Time-of-check Time-of-use (TOCTOU) Race ConditionThe product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.