CVE-2026-31548 Linux CVE debrief

Who should care

Defenders responsible for Linux kernel-based systems, particularly those using the affected versions, should assess exposure and prioritize patching. This includes operators managing Linux kernel deployments, platform administrators, vulnerability management teams, and security teams responsible for maintaining system security and integrity.

Why it matters

A vulnerability in the Linux kernel's cfg80211 subsystem has been addressed, and defenders should prioritize verifying and applying patches to prevent potential crashes and exploitation.

• Potential crashes due to undefined behavior
• Verification of patch application is necessary to prevent exploitation
• Defenders should review system configurations and update Linux kernel versions as necessary

Technical summary

The vulnerability is caused by a race condition in the cfg80211 subsystem of the Linux kernel. When a nl80211 socket that originated a PMSR request is closed, cfg80211_release_pmsr() sets the request's nl_portid to zero and schedules pmsr_free_wk to process the abort asynchronously. If the interface is concurrently torn down before that work runs, cfg80211_pmsr_wdev_down() calls cfg80211_pmsr_process_abort() directly. However, the already-scheduled pmsr_free_wk work item remains pending and may run after the interface has been removed from the driver.

Defensive priority

Defenders should prioritize verifying and applying patches for this vulnerability, particularly for systems using the affected Linux kernel versions.

Recommended defensive actions

• Verify and apply patches for this vulnerability
• Review system configurations and update Linux kernel versions as necessary
• Monitor system logs for potential exploitation attempts
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed
• Check relevant monitoring, detection, and logs for exposed assets that need extra review

Evidence notes

The vulnerability was introduced in the Linux kernel and has been resolved by canceling pmsr_free_wk synchronously in cfg80211_pmsr_wdev_down() before calling cfg80211_pmsr_process_abort(). This change ensures that any pending or in-progress work is drained before interface teardown proceeds, preventing the work from invoking the driver abort callback after the interface is gone. Defenders should verify patch application and review system configurations to prevent potential crashes and exploitation.

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.