CVE-2025-38352
Linux Kernel Time-of-Check Time-of-Use (TOCTOU) Race Condition Vulnerability
Does this matter?
Known to be exploited in the wild (CISA KEV, CISA remediation deadline 25 September 2025). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.
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.
- CVSS 3.1
- 7.8 HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 1.25% probability · 68th percentile
- CISA KEV
- Listed 4 September 2025 · due 25 September 2025
- Weakness
- CWE-367
- Affected
- linux/linux kernel · debian/debian linux
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
CISA notes
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. This vulnerability affects a common open-source component, third-party library, or a protocol used by different products. Please check with specific vendors for information on patching status. For more information, please see: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2c72fe18cc5f9f1750f5bc148cf1c94c29e106ff ; https://source.android.com/docs/security/bulletin/2025-09-01 ; https://nvd.nist.gov/vuln/detail/CVE-2025-38352
References
- https://git.kernel.org/stable/c/2c72fe18cc5f9f1750f5bc148cf1c94c29e106ffPatch
- https://git.kernel.org/stable/c/2f3daa04a9328220de46f0d5c919a6c0073a9f0bPatch
- https://git.kernel.org/stable/c/460188bc042a3f40f72d34b9f7fc6ee66b0b757bPatch
- https://git.kernel.org/stable/c/764a7a5dfda23f69919441f2eac2a83e7db6e5bbPatch
- https://git.kernel.org/stable/c/78a4b8e3795b31dae58762bc091bb0f4f74a2200Patch
- https://git.kernel.org/stable/c/c076635b3a42771ace7d276de8dc3bc76ee2ba1bPatch
- https://git.kernel.org/stable/c/c29d5318708e67ac13c1b6fc1007d179fb65b4d7Patch
- https://git.kernel.org/stable/c/f90fff1e152dedf52b932240ebbd670d83330ecaPatch
- https://lists.debian.org/debian-lts-announce/2025/10/msg00007.htmlMailing List, Third Party Advisory
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.htmlMailing List, Third Party Advisory
- https://github.com/farazsth98/chronomalyExploit
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-38352US Government Resource
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.