CVE-2026-31526 Linux CVE debrief

Who should care

Linux kernel developers and maintainers, BPF subsystem users, Linux distribution maintainers, and security teams responsible for vulnerability management and patching. These stakeholders should assess exposure and apply patches or mitigations to prevent potential denial-of-service or arbitrary code execution. They should also review compensating controls for exposed systems and monitor BPF subsystem usage and lock validation. Additionally, they should be a

Why it matters

CVE-2026-31526 is a medium-severity vulnerability in the Linux kernel's BPF subsystem. Linux kernel developers and maintainers, BPF subsystem users, and Linux distribution maintainers should assess exposure and apply patches or mitigations. The vulnerability requires verification of lock validation on exception exits from BPF subprograms.

• Local attackers may cause denial-of-service
• Potential execution of arbitrary code
• BPF subsystem lock validation failure

Technical summary

The vulnerability is caused by the incorrect handling of exception exits in BPF subprograms. The process_bpf_exit_full function passes check_lock = !curframe to check_resource_leak(), which can lead to the failure of validating active locks. The issue was resolved by setting check_lock to true for exception exits, regardless of the current frame. This change ensures that active locks are properly validated on exception exits from BPF subprograms, preventing potential denial-of-service or arbitrary code execution. Linux kernel developers and maintainers should assess exposure and apply patches or mitigations.

Defensive priority

Medium

Recommended defensive actions

• Review and apply patches from Linux kernel maintainers
• Update Linux kernel to version 6.18.21 or later
• Update Linux kernel to version 6.19.11 or later
• Monitor BPF subsystem usage and lock validation
• Perform compensating controls for exposed systems
• Track exceptions and retest remediated assets
• Review relevant monitoring, detection, and logs

Evidence notes

The vulnerability is caused by the incorrect setting of the check_lock variable in the process_bpf_exit_full function. This variable determines whether to validate active locks on exception exits from BPF subprograms. The issue was resolved by setting check_lock to true for exception exits, regardless of the current frame.

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.