RACE Between handle_posix_cpu_timers() and posix_cpu_timer_del() in Linux Kernel
CVE-2025-38352 Published on July 22, 2025

posix-cpu-timers: fix race between handle_posix_cpu_timers() and posix_cpu_timer_del()
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.

NVD

Known Exploited Vulnerability

This Linux Kernel Time-of-Check Time-of-Use (TOCTOU) Race Condition Vulnerability is part of CISA's list of Known Exploited Vulnerabilities. Linux kernel contains a time-of-check time-of-use (TOCTOU) race condition vulnerability that has a high impact on confidentiality, integrity, and availability.

The following remediation steps are recommended / required by September 25, 2025: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Vulnerability Analysis

CVE-2025-38352 is exploitable with local system access, and does not require authorization privileges or user interaction. This vulnerability is consided to have a high level of attack complexity. This vulnerability is known to be actively exploited by threat actors. The potential impact of an exploit of this vulnerability is considered to be very high.

Attack Vector:
LOCAL
Attack Complexity:
HIGH
Privileges Required:
NONE
User Interaction:
NONE
Scope:
UNCHANGED
Confidentiality Impact:
HIGH
Integrity Impact:
HIGH
Availability Impact:
HIGH

Weakness Type

What is a TOCTTOU Vulnerability?

The software 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. This can cause the software to perform invalid actions when the resource is in an unexpected state. This weakness can be security-relevant when an attacker can influence the state of the resource between check and use. This can happen with shared resources such as files, memory, or even variables in multithreaded programs.

CVE-2025-38352 has been classified to as a TOCTTOU vulnerability or weakness.


Products Associated with CVE-2025-38352

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Linux Kernel
 
Linux Kernel
 
Google Android
 
Canonical Ubuntu Linux
 

Affected Versions

Linux: Linux:

Exploit Probability

EPSS
0.08%
Percentile
22.51%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.