CVE-2026-63869: wifi: mac80211: limit injected antenna index in ieee80211_parse_tx_radiotap
In the Linux kernel, the following vulnerability has been resolved:
wifi: mac80211: limit injected antenna index in ieee80211parsetxradiotap
When parsing the radiotap header of an injected frame, ieee80211parsetxradiotap() uses the IEEE80211RADIOTAPANTENNA value directly as a shift count:
info->control.antennas |= BIT(iterator.thisarg);
iterator.thisarg 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: ieee80211parsetxradiotap+0xadb/0x1950 net/mac80211/tx.c:2174 ieee80211monitorstartxmit+0xb1f/0x1250 net/mac80211/tx.c:2451 ... packetsendmsg+0x3eb6/0x50f0 net/packet/afpacket.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.
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-63869?
The severity of CVE-2026-63869 is rated high with a score of 7.6.
How does CVE-2026-63869 affect the Linux kernel?
CVE-2026-63869 affects the Linux kernel by allowing improper handling of the IEEE80211_RADIOTAP_ANTENNA value during frame parsing.
What systems are vulnerable to CVE-2026-63869?
CVE-2026-63869 affects systems running affected versions of the Linux kernel with the mac80211 wireless subsystem.
How do I fix CVE-2026-63869?
To fix CVE-2026-63869, it is recommended to update the Linux kernel to a version that includes the security patch.
What are the potential impacts of exploiting CVE-2026-63869?
Exploiting CVE-2026-63869 could result in denial of service or execution of arbitrary code under certain conditions.