CVE-2026-63869 Linux CVE debrief

Who should care

Users of the Linux kernel, particularly those using wireless networking, should be aware of this vulnerability. This includes Linux kernel developers, maintainers, and users who rely on wireless networking functionality. Additionally, security teams and vulnerability management teams should review the Linux kernel's wireless networking components and ensure that the kernel is updated to a version that includes the fix.

Technical summary

The vulnerability exists in the ieee80211_parse_tx_radiotap function, where the IEEE80211_RADIOTAP_ANTENNA value is used directly as a shift count. This can cause undefined behavior when the value is greater than 64. The function is used to parse the radiotap header of an injected frame. To address this vulnerability, it is recommended to update the Linux kernel to the latest version, which includes a fix for this issue. Additionally, using a patched version of the ieee80211_parse_tx_radiotap function or monitoring for suspicious wireless network activity can help mitigate potential risks.

Defensive priority

Medium

Recommended defensive actions

• Update the Linux kernel to the latest version
• Use a patched version of the ieee80211_parse_tx_radiotap function
• Monitor for suspicious wireless network activity
• Review compensating controls for exposed systems
• 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
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance

Evidence notes

The vulnerability was reported by UBSAN and is caused by a shift-out-of-bounds error. This issue arises when the IEEE80211_RADIOTAP_ANTENNA value is used directly as a shift count in the ieee80211_parse_tx_radiotap function, which can lead to undefined behavior when the value exceeds 64. To verify and address this vulnerability, defenders should review the Linux kernel's wireless networking components, particularly the ieee80211_parse_tx_radiotap function, and ensure that the kernel is updated to a version that includes the fix. Additionally, monitoring for suspicious wireless network activity and reviewing compensating controls for exposed systems can help mitigate potential risks.

Official resources