SEPTEMBER 8, 2026
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Case File

CVE-2026-63869

HIGH · CVSS 7.6 EPSS 0.21%

Source: NVD + CISA KEV + EPSS · Published 2026-07-19 · Last synced 2026-08-18

CyberRota Analysis

AI-Generated

The vulnerability in the Linux kernel affects the mac80211 subsystem, specifically in the ieee80211_parse_tx_radiotap function, which improperly handles antenna index values from user-supplied frames. This flaw allows for potential out-of-bounds shifts, leading to undefined behavior that could be exploited to cause system instability or crashes. Organizations using affected Linux distributions, particularly those relying on wireless networking capabilities, should prioritize patching this vulnerability to mitigate risks associated with malicious frame injection.

CVE
CVE-2026-63869
Severity
HIGH
CVSS
7.6
EPSS
0.21%
Linux

Original NVD 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 ever be represented. Ignore any larger value instead of shifting out of bounds.