Linux Kernel up to 6.1.158/6.6.117/6.12.59/6.17.9 timers timer_shutdown_sync race condition

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4.6$0-$5k0.00

Summaryinfo

A vulnerability identified as critical has been detected in Linux Kernel up to 6.1.158/6.6.117/6.12.59/6.17.9. Affected by this issue is the function timer_shutdown_sync of the component timers. The manipulation leads to race condition. This vulnerability is documented as CVE-2025-68214. There is not any exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.1.158/6.6.117/6.12.59/6.17.9 and classified as critical. This issue affects the function timer_shutdown_sync of the component timers. The manipulation with an unknown input leads to a race condition vulnerability. Using CWE to declare the problem leads to CWE-362. The product contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently. Impacted is availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: timers: Fix NULL function pointer race in timer_shutdown_sync() There is a race condition between timer_shutdown_sync() and timer expiration that can lead to hitting a WARN_ON in expire_timers(). The issue occurs when timer_shutdown_sync() clears the timer function to NULL while the timer is still running on another CPU. The race scenario looks like this: CPU0 CPU1 <SOFTIRQ> lock_timer_base() expire_timers() base->running_timer = timer; unlock_timer_base() [call_timer_fn enter] mod_timer() ... timer_shutdown_sync() lock_timer_base() // For now, will not detach the timer but only clear its function to NULL if (base->running_timer != timer) ret = detach_if_pending(timer, base, true); if (shutdown) timer->function = NULL; unlock_timer_base() [call_timer_fn exit] lock_timer_base() base->running_timer = NULL; unlock_timer_base() ... // Now timer is pending while its function set to NULL. // next timer trigger <SOFTIRQ> expire_timers() WARN_ON_ONCE(!fn) // hit ... lock_timer_base() // Now timer will detach if (base->running_timer != timer) ret = detach_if_pending(timer, base, true); if (shutdown) timer->function = NULL; unlock_timer_base() The problem is that timer_shutdown_sync() clears the timer function regardless of whether the timer is currently running. This can leave a pending timer with a NULL function pointer, which triggers the WARN_ON_ONCE(!fn) check in expire_timers(). Fix this by only clearing the timer function when actually detaching the timer. If the timer is running, leave the function pointer intact, which is safe because the timer will be properly detached when it finishes running.

The advisory is shared at git.kernel.org. The identification of this vulnerability is CVE-2025-68214 since 12/16/2025. The exploitation is known to be difficult. Technical details are known, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 282382 (Amazon Linux 2023 : bpftool, kernel, kernel-devel (ALAS2023-2025-1350)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.1.159, 6.6.118, 6.12.60 or 6.17.10 eliminates this vulnerability. Applying the patch 1a975716cc8977f461e45e28e3e5977d46ad7a6a/6665fbd7730b26d770c232b20d1b907e6a67a914/176725f4848376530a0f0da9023f956afcc33585/a01efa7a780c42ac5170a949bd95c9786ffcc60a/20739af07383e6eb1ec59dcd70b72ebfa9ac362c is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (282382) and CERT Bund (WID-SEC-2025-2868). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Affected

  • Debian Linux
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • SUSE openSUSE
  • RESF Rocky Linux
  • Open Source Linux Kernel

Productinfo

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Version

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Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.8
VulDB Meta Temp Score: 4.6

VulDB Base Score: 4.8
VulDB Temp Score: 4.6
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 4.7
NVD Vector: 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Race condition
CWE: CWE-362
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 282382
Nessus Name: Amazon Linux 2023 : bpftool, kernel, kernel-devel (ALAS2023-2025-1350)

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.1.159/6.6.118/6.12.60/6.17.10
Patch: 1a975716cc8977f461e45e28e3e5977d46ad7a6a/6665fbd7730b26d770c232b20d1b907e6a67a914/176725f4848376530a0f0da9023f956afcc33585/a01efa7a780c42ac5170a949bd95c9786ffcc60a/20739af07383e6eb1ec59dcd70b72ebfa9ac362c

Timelineinfo

12/16/2025 Advisory disclosed
12/16/2025 +0 days CVE reserved
12/16/2025 +0 days VulDB entry created
02/26/2026 +72 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2025-68214 (🔒)
GCVE (CVE): GCVE-0-2025-68214
GCVE (VulDB): GCVE-100-336821
CERT Bund: WID-SEC-2025-2868 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 12/16/2025 16:13
Updated: 02/26/2026 17:00
Changes: 12/16/2025 16:13 (59), 12/17/2025 08:03 (1), 01/09/2026 06:23 (2), 01/20/2026 00:41 (7), 02/03/2026 07:17 (1), 02/21/2026 15:14 (1), 02/26/2026 17:00 (9)
Complete: 🔍
Cache ID: 216::103

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