CVE-2026-63869

/// Technical description

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

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References