CVE-2026-31555: Linux kernel · futex: Clear stale exiting pointer in futex_lock_pi() retry path Fuzzying/stressing
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.5 Medium · fixed in 5.15.0-1112.119~20.04.1 : update Linux kernel when convenient.
Data as of 26 Oct 2026, 17:16 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 2% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 5.15.0-1112.119~20.04.1, 5.15.0-1117.126~20.04.1, 5.15.0-1117.126~20.04.2 +63
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 24 Apr 2026
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 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde@7.0.0-1008.8?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 25.10linuxpkg:deb/ubuntu/linux?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-gcppkg:deb/ubuntu/linux-gcp?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 for this vulnerability. Users should apply the updated linux-aws kernel versions that include the fix. The vendor advisory confirms the issue is resolved in patched releases. No additional mitigation steps are required beyond applying the official fix.
Description
A vulnerability in the Linux kernel's futex subsystem (CVE-2026-31555) has been resolved. The issue involved a stale pointer in the futex_lock_pi() retry path, where a reference to an exiting task was not properly cleared, potentially causing kernel warnings or instability. This flaw was fixed by resetting the pointer upon retry to prevent use of a stale reference. The vulnerability affects specific linux-aws kernel versions. The CVSS score is 5.5 (medium severity) with impact limited to availability. A patch is available and should be applied.
References
- ubuntu.com/security/CVE-2026-31555 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-31555 (opens in a new tab)
- git.kernel.org/linus/210d36d892de5195e6766c45519dfb1e65f3eb83 (opens in a new tab)
- git.kernel.org/stable/c/210d36d892de5195e6766c45519dfb1e65f3eb83 (opens in a new tab)
- git.kernel.org/stable/c/33095ae3bdde5e5c264d7e88a2f3e7703a26c7aa (opens in a new tab)
- git.kernel.org/stable/c/5e8e06bf8909e79b4acd950cf578cfc2f10bbefa (opens in a new tab)
- git.kernel.org/stable/c/71112e62807d1925dc3ae6188b11f8cfc85aec23 (opens in a new tab)
- git.kernel.org/stable/c/7475dfad10a05a5bfadebf5f2499bd61b19ed293 (opens in a new tab)
- git.kernel.org/stable/c/92e47ad03e03dbb5515bdf06444bf6b1e147310d (opens in a new tab)
- git.kernel.org/stable/c/de7c0c04ad868f2cee6671b11c0a6d20421af1da (opens in a new tab)
- git.kernel.org/stable/c/e7824ec168d2ac883a213cd1f4d6cc0816002a85 (opens in a new tab)
- ubuntu.com/security/notices/USN-8567-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8574-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8575-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8576-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8574-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8595-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8596-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8575-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8576-2 (opens in a new tab)