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

High severity, CVSS 7.8. Actively exploited: in CISA KEV since 2025-09-04. EPSS: 1.3% chance of exploitation in the next 30 days.

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.

Affected products

• Debian Debian Linux: version 11.0 only
• Linux Linux Kernel: from 2.6.36, before 5.4.295 (fixed in 5.4.295); from 5.5, before 5.10.239 (fixed in 5.10.239); from 5.11, before 5.15.186 (fixed in 5.15.186); from 5.16, before 6.1.142 (fixed in 6.1.142); from 6.2, before 6.6.94 (fixed in 6.6.94); from 6.7, before 6.12.34 (fixed in 6.12.34); …

Published 2025-07-22. Last modified 2026-09-08.