CVE-2025-39745: Linux kernel · rcutorture: Fix rcutorture_one_extend_check() splat in RT kernels
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.5 Medium.
Data as of 26 Oct 2026, 10:12 UTC
- 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:HExploitation evidence
Disclosed: evidence found.
CVE published 11 Sep 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde@6.17.0-1017.17?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinuxpkg:deb/ubuntu/linux@6.8.0-136.136?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinux-awspkg:deb/ubuntu/linux-aws@6.8.0-1060.63?arch=source&distro=nobleOther threats | Affected
| 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 threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure@6.8.0-1062.69?arch=source&distro=nobleOther threats | Affected
| 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 threats | Affected
| 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
- ubuntu.com/security/CVE-2025-39745 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2025-39745 (opens in a new tab)
- git.kernel.org/linus/8d71351d88e478d3c4e945e3218e97ec677fd807 (opens in a new tab)
- git.kernel.org/stable/c/69c5ae0f441c2d72e8f48dc1e08464c172360c4c (opens in a new tab)
- git.kernel.org/stable/c/8d71351d88e478d3c4e945e3218e97ec677fd807 (opens in a new tab)
- git.kernel.org/stable/c/a85550267247cdf5e7499be00ea8e388ab014e50 (opens in a new tab)