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

Q: How do I fix CVE-2025-38352?

linux kernel: upgrade to 5.4.295, 5.10.239, 5.15.186, 6.1.142, 6.6.94, 6.12.34, 6.15.3; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2025-38352 being exploited?

Yes. CVE-2025-38352 is on the CISA Known Exploited Vulnerabilities list, so treat it as patch-now.

Q: What does CVE-2025-38352 affect?

CVE-2025-38352 affects linux kernel, debian linux. Severity is high (CVSS 7.8). 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 handl

Q: How urgent is CVE-2025-38352?

Priority 80/100. High severity; Exploited in the wild (CISA KEV); Public exploit reference; On your watchlist

Patch now

HIGH 7.8EXPLOITEDWATCHLISTUPGRADEMITIGATE

CVE-2025-38352 is a high-severity flaw (CVSS 7.8) affecting linux kernel, debian linux, reported as exploited in the wild. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

High severity
Exploited in the wild (CISA KEV)
Public exploit reference
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	7.8 (High)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	1.4% (top 28%)
CISA exploited list	Yes, fix due 2025-09-25
Weakness	CWE-367
Published	2025-07-22
Last modified	2026-09-08

Publisher (CNA): kernel.org · Vendor: debian · linux

Last updated 2026-09-08 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2025-07-22 08:15 UTCPublished CVE record published
2025-09-04Exploited Added to the CISA Known Exploited Vulnerabilities list
2025-09-25Deadline CISA due date for US federal agencies to patch
2026-09-08 18:17 UTCUpdated Record last modified

linux linux kernel UPGRADE

Affected: >= 2.6.36 and < 5.4.295 · >= 5.5 and < 5.10.239 · >= 5.11 and < 5.15.186 · >= 5.16 and < 6.1.142 · >= 6.2 and < 6.6.94 · >= 6.7 and < 6.12.34 · >= 6.13 and < 6.15.3 · 6.16 rc1

Fixed in: 5.4.295, 5.10.239, 5.15.186, 6.1.142, 6.6.94, 6.12.34, 6.15.3

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

debian debian linux MITIGATE

Affected: 11.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 11.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.

Fedora 46 · R · FIXED · 4.6.2-1.fc46 · FEDORA-2026-1dd919a262 · source

sudo dnf upgrade --advisory=FEDORA-2026-1dd919a262

Fedora ELN · perl-Mail-AuthenticationResults · FIXED · 2.20261029-1.eln159 · FEDORA-2026-a2c11d7da6 · source

sudo dnf upgrade --advisory=FEDORA-2026-a2c11d7da6

Ubuntu 24.04 · linux · FIXED · 6.8.0-87.88

sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "6.8.0-87.88" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 25.04 · linux · FIXED · 6.14.0-32.32

sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "6.14.0-32.32" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 22.04 · linux · FIXED · 5.15.0-156.166

sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "5.15.0-156.166" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 25.10 · linux · NOT AFFECTED

Ubuntu 20.04 · linux · FIXED · 5.4.0-223.243

sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "5.4.0-223.243" && echo PATCHED || echo STILL-VULNERABLE

Debian 12 · linux · FIXED · 6.1.147-1

sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "6.1.147-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · linux · FIXED · 6.12.35-1

sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "6.12.35-1" && echo PATCHED || echo STILL-VULNERABLE

RHEL 10 · kernel · FIXED · kernel-6.12.0-55.32.1.el10_0

sudo dnf upgrade --advisory=RHSA-2025:15662 rpm -q kernel

RHEL 7 Extended Lifecycle Support · kernel-rt · FIXED · kernel-rt-3.10.0-1160.139.1.rt56.1291.el7

sudo dnf upgrade --advisory=RHSA-2025:15646 rpm -q kernel-rt

RHEL 7 Extended Lifecycle Support · kernel · FIXED · kernel-3.10.0-1160.139.1.el7

sudo dnf upgrade --advisory=RHSA-2025:15648 rpm -q kernel

RHEL 8 · kernel-rt · FIXED · kernel-rt-4.18.0-553.74.1.rt7.415.el8_10

sudo dnf upgrade --advisory=RHSA-2025:15472 rpm -q kernel-rt

RHEL 8 · kernel · FIXED · kernel-4.18.0-553.74.1.el8_10

sudo dnf upgrade --advisory=RHSA-2025:15471 rpm -q kernel

Amazon Linux 2023 · see advisory · FIXED · ALAS2023-2025-1111 · source

sudo dnf update --advisory=ALAS2023-2025-1111

Amazon Linux 2 · see advisory · FIXED · ALAS2-2025-2988 · source

sudo yum update --advisory=ALAS2-2025-2988

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

GitHub PoC: farazsth98/chronomaly (312 stars)
GitHub PoC: farazsth98/poc-CVE-2025-38352 (119 stars)
GitHub PoC: AnalyticETH/chronomaly-webos (17 stars)

Verify at the official source NVD · CVE Program · CISA KEV catalog · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2025-38352?

linux kernel: upgrade to 5.4.295, 5.10.239, 5.15.186, 6.1.142, 6.6.94, 6.12.34, 6.15.3; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2025-38352 being exploited?

Yes. CVE-2025-38352 is on the CISA Known Exploited Vulnerabilities list, so treat it as patch-now.

What does CVE-2025-38352 affect?

CVE-2025-38352 affects linux kernel, debian linux. Severity is high (CVSS 7.8). 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 handl

How urgent is CVE-2025-38352?

Priority 80/100. High severity; Exploited in the wild (CISA KEV); Public exploit reference; On your watchlist

Software pages

Linux kernel vulnerabilities · Debian vulnerabilities

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References

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