# CVE-2026-63869: wifi: mac80211: limit injected antenna index in ieee80211_parse_tx_radiotap

> A local attacker can trigger a shift-out-of-bounds error in the Linux kernel Wi-Fi subsystem by injecting a malformed radiotap header, causing a system crash.

- **Severity:** High 7.6 (`CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 19 Jul 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-63869, DEBIAN-CVE-2026-63869, GHSA-p8w8-3vc5-9f6x, UBUNTU-CVE-2026-63869

## What is CVE-2026-63869?

CVE-2026-63869 is a high-severity vulnerability in Linux kernel, published on 19 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official 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.

Weakness: CWE-1284 (Improper Validation of Specified Quantity in Input), CWE-190 (Integer Overflow or Wraparound)

## Which versions are affected by CVE-2026-63869?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-63869?

Apply the vendor's patch.

## Is CVE-2026-63869 being exploited?

There is no known exploitation of CVE-2026-63869 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-63869 and fix it if it is affected.

What it is: CVE-2026-63869 is a high-severity vulnerability in Linux kernel, published on 19 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-63869 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-63869/ (Markdown: https://insights.sbomify.com/CVE-2026-63869/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-63869
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-63869
- OSV: https://osv.dev/vulnerability/CVE-2026-63869

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-63869/
Summaries are generated and may contain mistakes; the official description above is the record.