cyfenced.com →

[ CVE-2025-38352 · Published 22 Jul 2025 ]

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

Exploited · CISA KEV CVSS 7.8 EPSS 1%1 agency advisoryFix available

[ Why it matters ]Priority signals

  • Exploited in the wild: on CISA's Known Exploited Vulnerabilities list since 2025-09-04

[ Description ]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.

CISA: Linux kernel contains a time-of-check time-of-use (TOCTOU) race condition vulnerability that has a high impact on confidentiality, integrity, and availability.

[ Fixes ]Fixes and patches

CISA required action (US federal deadline 25 Sep 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.

[ Advisories ]Government CERT advisories

  • CERT-FRCERTFR-2026-AVI-1286

    Multiple vulnerabilities in the Ubuntu Linux kernel Translated from French

    Multiple vulnerabilities have been discovered in the Ubuntu Linux kernel. Some of them allow an attacker to cause privilege escalation, remote denial of service and a breach of data confidentiality.

    CVE-2022-27664CVE-2022-3114CVE-2022-41723+2211 more CVEs

[ References ]References