CVE-2026-31555 Linux CVE debrief

Who should care

Linux kernel users and administrators should be aware of this vulnerability and take steps to mitigate it. This vulnerability has been resolved in the Linux kernel. Affected operators, platforms, vulnerability-management, and security teams should review the official patches and apply them accordingly.

Technical summary

The vulnerability is caused by a use-after-free error in the futex subsystem. When futex_lock_pi_atomic() returns -EBUSY and stores a refcounted task pointer in 'exiting', the local pointer is not reset to nil after wait_for_owner_exiting() consumes the reference. This can cause a bogus pointer to be passed to wait_for_owner_exiting() on a retry, leading to a use-after-free error. The affected product is the Linux kernel.

Defensive priority

Medium

Recommended defensive actions

• Apply the official patches provided by the Linux kernel maintainers.
• Ensure that the Linux kernel is updated to a version that includes the fix.
• Monitor system logs for potential exploitation attempts.
• Review compensating controls for exposed systems while remediation is scheduled and verified.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.
• Perform an exposure review to identify potentially affected systems.

Evidence notes

The CVE record was published on 2026-04-24T15:16:29.837Z and was last modified on 2026-07-14T13:18:45.463Z. The NVD entry is currently Modified. This vulnerability affects Linux kernel users and administrators. Evidence of exploitation attempts may be found in system logs. Further verification is required to confirm the scope of affected systems.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.