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VulnerabilityPublished Updated

CVE-2025-39745: Linux kernel · rcutorture: Fix rcutorture_one_extend_check() splat in RT kernels

Affects Linux kernelSource GCVE Database

0

Not known to be exploited · CVSS 5.5 Medium.

Data as of 26 Oct 2026, 10:12 UTC

CVSS 3.1 base score
5.5Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 4% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 11 Sep 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde@6.17.0-1017.17?arch=source&distro=questingOther threatsAffected
  • 6.17.0-1003.3 – 6.17.0-1017.17
10 affected builds
Fixed in–
Ubuntu 24.04 LTSlinuxpkg:deb/ubuntu/linux@6.8.0-136.136?arch=source&distro=nobleOther threatsAffected
  • 6.5.0-9.9 – 6.8.0-136.136
53 affected builds
Fixed in–
Ubuntu 24.04 LTSlinux-awspkg:deb/ubuntu/linux-aws@6.8.0-1060.63?arch=source&distro=nobleOther threatsAffected
  • 6.5.0-1008.8 – 6.8.0-1060.63
48 affected builds
Fixed in–
Ubuntu 24.04 LTSlinux-aws-6.14pkg:deb/ubuntu/linux-aws-6.14@6.14.0-1018.18~24.04.1?arch=source&distro=nobleOther threatsAffected
  • 6.14.0-1007.7~24.04.1 – 6.14.0-1018.18~24.04.1
11 affected builds
Fixed in–
Ubuntu 24.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure@6.8.0-1062.69?arch=source&distro=nobleOther threatsAffected
  • 6.5.0-1007.7 – 6.8.0-1062.69
39 affected builds
Fixed in–
Ubuntu 24.04 LTSlinux-azure-6.11pkg:deb/ubuntu/linux-azure-6.11@6.11.0-1018.18~24.04.1?arch=source&distro=nobleOther threatsAffected
  • 6.11.0-1008.8~24.04.1 – 6.11.0-1018.18~24.04.1
7 affected builds
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix is available and has been applied to the Linux kernel source to correct the rcutorture_one_extend_check() function. Users running RT kernels with CONFIG_PREEMPT_RT=y should update to a kernel version that includes this fix to avoid kernel crashes during rcutorture testing.

Description

A vulnerability in the Linux kernel's rcutorture test tool caused a kernel crash (splat) on real-time (RT) kernels built with CONFIG_PREEMPT_RT=y. The issue was due to incorrect handling of softirq disabling checks in the rcutorture_one_extend_check() function. This has been fixed by changing the check to use softirq_count() instead of preempt_count().

References

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