CVE-2026-80775 Linux CVE debrief

Who should care

Linux kernel developers and maintainers, Linux distribution vendors, and users of Linux-based systems should assess exposure and apply patches to prevent exploitation. Affected operators must review and apply patches or mitigations, and verify system logs for potential exploitation attempts. Vulnerability management and security teams should track exceptions, retest remediated assets, and monitor system logs for potential exploitation attempts.

Why it matters

A race condition vulnerability in the Linux kernel's futex subsystem can lead to a use-after-free vulnerability, potentially allowing denial-of-service (DoS) or privilege escalation attacks. Linux kernel developers and maintainers, Linux distribution vendors, and users of Linux-based systems should assess exposure and apply patches to prevent exploitation.

• Potential use-after-free vulnerability when multiple tasks attempt to set futex hash slots simultaneously
• Possible denial-of-service (DoS) or privilege escalation attacks
• Need to verify and apply patches to prevent exploitation

Technical summary

The vulnerability occurs in the Linux kernel's futex subsystem, specifically in the futex_hash_allocate() function. A race condition can occur when a vfork child calls vfork again and is then killed with SIGKILL, allowing the parent to run concurrently with the grandchild in the same mm. This can lead to a use-after-free vulnerability when multiple tasks attempt to set the futex hash slots simultaneously.

Defensive priority

Medium

Recommended defensive actions

• Review and apply the patch to the Linux kernel
• Monitor system logs for potential exploitation attempts
• Consider implementing additional security measures to prevent vfork-based attacks
• 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
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The vulnerability was introduced by a commit that moved the allocation of mm->futex.phash.ref without proper locking. The issue can be triggered when a vfork child calls vfork again and is then killed with SIGKILL, allowing the parent to run concurrently with the grandchild in the same mm.

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.