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

Exploited in the wild High 7.8 Published 22 Jul 2025 Updated 8 Sep 2026

A race condition in Linux kernel posix-cpu-timers allows a local attacker to cause a denial of service by triggering a use-after-free scenario during task exit.

Exploited in the wild: Since 4 Sep 2025
Login needed: Any signed-in user
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

What is CVE-2025-38352?

CVE-2025-38352 is a high-severity vulnerability in Debian Debian Linux, published on 22 Jul 2025. It can only be exploited from the same machine or local network, with no action from the victim.

Official 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.

Weakness: CWE-367

Which versions are affected by CVE-2025-38352?

It affects 2 products.

Linux distribution packages (40)

`kernel-abi-stablelists` AlmaLinux:10	All versions	`6.12.0-55.32.1.el10_0`
`kernel-doc` AlmaLinux:10	All versions	`6.12.0-55.32.1.el10_0`
`kernel` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-64k` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-64k-core` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-64k-debug` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-64k-debug-core` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-64k-debug-debuginfo` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-64k-debug-devel` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-64k-debug-devel-matched` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-64k-debug-modules` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-64k-debug-modules-core` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-64k-debug-modules-extra` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-64k-debuginfo` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-64k-devel` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-64k-devel-matched` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-64k-modules` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-64k-modules-core` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-64k-modules-extra` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-abi-stablelists` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-core` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-debug` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-debug-core` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-debug-debuginfo` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-debug-devel` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-debug-devel-matched` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-debug-modules` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-debug-modules-core` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-debug-modules-extra` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-debug-uki-virt` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-debuginfo` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-debuginfo-common-aarch64` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-debuginfo-common-ppc64le` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-debuginfo-common-s390x` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-debuginfo-common-x86_64` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-devel` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-devel-matched` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-modules` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-modules-core` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`
`kernel-modules-extra` Red Hat:enterprise_linux:10.0	All versions	`0:6.12.0-55.32.1.el10_0`

Products include Debian Debian Linux, Linux kernel.

How do I fix CVE-2025-38352?

Apply the vendor's patch. US federal agencies must fix it by 25 Sep 2025.

Is CVE-2025-38352 being exploited?

Yes. Attackers have exploited CVE-2025-38352 in the wild since at least 4 Sep 2025.

Public exploit code: 6 proofs of concept on GitHub.

All Debian Debian Linux vulnerabilities

Sources

Also known as A-425282960, ALSA-2025:15662, ASB-A-425282960, BELL-CVE-2025-38352, DEBIAN-CVE-2025-38352, GHSA-mr4j-mh66-4679 and 7 more.