CVE-2025-39977: Linux kernel · futex: Prevent use-after-free during requeue-PI
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.8 High · fixed in 6.8.0-1050.53~22.04.1 : patch Linux kernel soon.
Data as of 26 Oct 2026, 14:05 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.
- Patch
- Available – fixed in 6.8.0-1050.53~22.04.1, 6.8.0-1051.57~22.04.1, 6.8.0-1052.55~22.04.1 +32
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 15 Oct 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
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 25.10linuxpkg:deb/ubuntu/linux@6.17.0-6.6?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-awspkg:deb/ubuntu/linux-aws@6.17.0-1003.3?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure@6.17.0-1006.6?arch=source&distro=questingOther threats | 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 25.10linux-gcppkg:deb/ubuntu/linux-gcp@6.17.0-1003.3?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-oraclepkg:deb/ubuntu/linux-oracle@6.17.0-1003.3?arch=source&distro=questingOther 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 patch is available and should be applied to affected Linux kernel versions. The Ubuntu security advisory USN-8095-1 confirms the fix is included in updated linux-hwe-edge kernel packages. Users should update to the fixed kernel versions as provided by their distribution. No additional mitigations are indicated by the vendor advisory.
Description
A use-after-free vulnerability in the Linux kernel futex subsystem related to requeue-PI operations has been resolved. The flaw involves improper synchronization in futex_wait_requeue_pi(), which can lead to use of freed memory during task wakeup. This issue was detected by syzbot and fixed by ensuring futex_q::task is read before updating the requeue state to prevent race conditions. The vulnerability affects multiple specific Linux kernel versions in the linux-hwe-edge product line. A patch is available and has been released by Ubuntu as part of a broader Linux kernel security update addressing multiple issues.
References
- ubuntu.com/security/CVE-2025-39977 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2025-39977 (opens in a new tab)
- git.kernel.org/linus/b549113738e8c751b613118032a724b772aa83f2 (opens in a new tab)
- git.kernel.org/stable/c/348736955ed6ca6e99ca24b93b1d3fbfe352c181 (opens in a new tab)
- git.kernel.org/stable/c/a170b9c0dde83312b8b58ccc91509c7c15711641 (opens in a new tab)
- git.kernel.org/stable/c/b549113738e8c751b613118032a724b772aa83f2 (opens in a new tab)
- git.kernel.org/stable/c/cb5d19a61274b51b49601214a87af573b43d60fa (opens in a new tab)
- git.kernel.org/stable/c/d824b2dbdcfe3c390278dd9652ea526168ef6850 (opens in a new tab)
- ubuntu.com/security/notices/USN-8095-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8100-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8095-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8095-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8095-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-8125-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8126-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8095-5 (opens in a new tab)
- ubuntu.com/security/notices/USN-8165-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8261-1 (opens in a new tab)