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Linux Kernel Time-of-Check Time-of-Use (TOCTOU) Race Condition Vulnerability

CVE-2025-38352

What this means

This is rated high severity (7.8 out of 10). It is on the known-exploited catalogue, which means attacks using it have already been seen. Ask IT whether Linux Linux Kernel and Debian Debian Linux are in your estate, and treat that as the priority.

Full vendor 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.

Scoring and exploitation

7.8/ 10
CVSS 3.1 base scoreHigh

Exploitable only with local access and a low-privilege account, and no one has to click or open anything. High impact on confidentiality, integrity and availability.

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitability

Longer bar: easier to attack

Attack vectorLocalAV:L
Attack complexityLowAC:L
Privileges requiredLowPR:L
User interactionNoneUI:N
ScopeUnchangedS:U

Impact

Longer bar: more harm

ConfidentialityHighC:H
IntegrityHighI:H
AvailabilityHighA:H
~1.4% estimated chance of attack in 30 daysModel estimate (): a probability signal, not confirmed exploitation
Exploited in the wild
Yes — confirmed exploitation (US CISA )
Not reported
Listed product
Linux Kernel

Weaknesses

CWE-367

Affected products ()

  • Linux Linux Kernel
  • Debian Debian Linux
Show the raw CPE strings (3)
  • cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
  • cpe:2.3:o:linux:linux_kernel:6.16:rc1:*:*:*:*:*:*
  • cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*

References

12 links from the CVE record, grouped by site.

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