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🐧 Linux
CISA KEV · ACTIVELY EXPLOITED
HIGH severity

CVE-2025-38352 — Kernel

HIGH

CVE-2025-38352 is a high-severity (CVSS 7.8) CWE-367 vulnerability in Kernel. It is in CISA's Known Exploited Vulnerabilities catalog (added 2025-09-04) — treat it as actively exploited and patch now. A fix is available for Kernel — see the affected versions and patch details below.

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

Also known asA-425282960ASB-A-425282960
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
3 known
Exploitation data as of Oct 23, 2026 · OSV.dev, NVD, CISA KEV, FIRST.org (EPSS)

Exploitation Status

Actively exploited in the wild

  • Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2025-09-04. Federal agencies were required to remediate by 2025-09-25.
  • A successful exploit gives an attacker total control of the affected component, not partial access.

Exploitation and automatability from CISA (KEV catalog and SSVC triage) for CVE-2025-38352.

EPSS Exploitation Probability

via FIRST.org ↗
1.4%probability of exploitation in next 30 days
Lower Risk+0.07%
Lower risk than most CVEs71th percentile — riskier than 71% of all scored CVEsHighest risk
0.00%0.62%1.24%1.86%0.1%1.4%Apr 26Aug 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2025-38352 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 394,803 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected
🐧Kernel

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Linux packages — download data is not available via public APIs for these ecosystems.

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.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐧LinuxKernel≥ 2.6.36&&< 5.4.2955.4.295

Affected Products

2 products · 9 configurations
OS
debian linuxdebian
1 version
11.0
OS
linux kernellinux
≥ 6.13 && < 6.15.3
1 version
6.16
Exploits & PoCs
3

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Kernel, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update Kernel to 5.4.295 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-38352 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

This CVE is rated with Important severity because it may allow an attacker with local user access to escalate their privileges on a target system.

Workaround published by Red Hat
Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
Source: Red Hat security advisory for CVE-2025-38352 (CC BY 4.0)
ProductFixed inAdvisory
Red Hat Enterprise Linux 10kernel-0:6.12.0-55.32.1.el10_0RHSA-2025:15662
Red Hat Enterprise Linux 7 Extended Lifecycle Supportkernel-rt-0:3.10.0-1160.139.1.rt56.1291.el7RHSA-2025:15646
Red Hat Enterprise Linux 7 Extended Lifecycle Supportkernel-0:3.10.0-1160.139.1.el7RHSA-2025:15648
Red Hat Enterprise Linux 8kernel-rt-0:4.18.0-553.74.1.rt7.415.el8_10RHSA-2025:15472
Red Hat Enterprise Linux 8kernel-0:4.18.0-553.74.1.el8_10RHSA-2025:15471
Red Hat Enterprise Linux 8kpatch-patchRHSA-2025:15921
Red Hat Enterprise Linux 8.2 Advanced Update Supportkernel-0:4.18.0-193.168.1.el8_2RHSA-2025:15656
Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Supportkernel-0:4.18.0-305.172.1.el8_4RHSA-2025:15660

Frequently Asked Questions

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
O3 Security · Impact-Aware SCA

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Actively Exploited: CVE-2025-38352: Kernel (High 7.8)