CVE-2026-98406 Linux CVE debrief

Who should care

Defenders responsible for Linux kernel-based systems, particularly those using mac80211, should assess exposure and prioritize patching or implementing compensating controls. They should verify if their Linux kernel versions are affected and apply patches if available to prevent potential issues. They should also monitor for similar issues in the Linux kernel's mac80211 to ensure timely detection and response.

Why it matters

CVE-2026-98406 is a vulnerability in the Linux kernel's mac80211 that triggers a warning when setting the bitrate mask for a network interface not in the driver. Defenders should prioritize verifying affected versions, applying patches, and monitoring for similar issues.

• Defenders need to verify if their Linux kernel versions are affected and apply patches if available to prevent potential issues.
• They should also monitor for similar issues in the Linux kernel's mac80211 to ensure timely detection and response.
• Implementing compensating controls can help detect and prevent exploitation of this vulnerability.

Technical summary

The Linux kernel's mac80211 has a vulnerability that triggers a warning (WARN) when setting the bitrate mask for a network interface that is not in the driver. This occurs because the check for the interface being in the driver is missing. The issue is caused by a missing check for the interface being in the driver in ieee80211_set_bitrate_mask(). The WARN is triggered when the interface is being torn down or when the wext ioctl is issued during interface bringup before drv_add_interface() sets IN_DRIVER. Defenders should prioritize verifying if their Linux kernel versions are affected and apply patches if available.

Defensive priority

Defenders should prioritize verifying if their Linux kernel versions are affected and apply patches if available. They should also monitor for similar issues in the Linux kernel's mac80211 and consider implementing compensating controls to detect and prevent exploitation.

Recommended defensive actions

• Verify if the Linux kernel version is affected and apply patches if available
• Monitor for similar issues in the Linux kernel's mac80211
• Consider implementing compensating controls to detect and prevent exploitation
• 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
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The issue is caused by a missing check for the interface being in the driver in ieee80211_set_bitrate_mask(). The WARN is triggered when the interface is being torn down or when the wext ioctl is issued during interface bringup before drv_add_interface() sets IN_DRIVER.

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.