PT-2026-61186 · Linux · Linux

CVE-2026-63869 · Published 2026-07-19 · Updated 2026-07-19

Mitre

CVSS v3.1

7.6

High

Base vector

AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L

In the Linux kernel, the following vulnerability has been resolved:

wifi: mac80211: limit injected antenna index in ieee80211 parse tx radiotap

When parsing the radiotap header of an injected frame, ieee80211 parse tx radiotap() uses the IEEE80211 RADIOTAP ANTENNA value directly as a shift count:

info->control.antennas |= BIT(*iterator.this arg);

*iterator.this arg is an 8-bit value taken straight from the frame supplied by userspace, so BIT() can be asked to shift by up to 255. That is undefined behaviour on the unsigned long and is reported by UBSAN:

UBSAN: shift-out-of-bounds in net/mac80211/tx.c:2174:30 shift exponent 235 is too large for 64-bit type 'unsigned long' Call Trace: ieee80211 parse tx radiotap+0xadb/0x1950 net/mac80211/tx.c:2174 ieee80211 monitor start xmit+0xb1f/0x1250 net/mac80211/tx.c:2451 ... packet sendmsg+0x3eb6/0x50f0 net/packet/af packet.c:3109

info->control.antennas is a 2-bit bitmap (u8 antennas:2), so only antenna indices 0 and 1 can ever be represented. Ignore any larger value instead of shifting out of bounds.

Fix

Related Identifiers

CVE-2026-63869

Affected Products

Linux

References · 5

• https://nvd.nist.gov/vuln/detail/CVE-2026-63869 · Security Note
• https://git.kernel.org/stable/c/f6d3dc8e8492bf8435e0b23c99472af7bafd6b44 · Note
• https://git.kernel.org/stable/c/9b40c59bab08f2a99abf969cc0bb92fa49de004b · Note
• https://git.kernel.org/stable/c/6c0cf89f36ac0c0fd8687a4ccdce2efb23a9c663 · Note
• https://git.kernel.org/stable/c/033ce021a220913ac02416fcb5ac883a9ff8b6c7 · Note