# CVE-2026-72003: wifi: brcmfmac: cyw: fix heap overflow on a short auth frame

> A heap overflow in the Linux kernel brcmfmac Wi-Fi driver allows remote attackers to execute code or cause a denial of service via a short authentication frame.

- **Severity:** High 8.8 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Aug 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-72003, DEBIAN-CVE-2026-72003, GHSA-chrv-c8hf-p9c7, UBUNTU-CVE-2026-72003

## What is CVE-2026-72003?

CVE-2026-72003 is a high-severity memory corruption vulnerability in Linux, published on 15 Aug 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: brcmfmac: cyw: fix heap overflow on a short auth frame

brcmf_notify_auth_frame_rx() takes the frame length from the firmware
event and copies the frame body with the management header offset
subtracted:

	u32 mgmt_frame_len = e->datalen - sizeof(struct brcmf_rx_mgmt_data);
	...
	memcpy(&mgmt_frame->u, frame,
	       mgmt_frame_len - offsetof(struct ieee80211_mgmt, u));

The only length check is e->datalen >= sizeof(*rxframe), so mgmt_frame_len
can be anything from 0 up. offsetof(struct ieee80211_mgmt, u) is 24. When
mgmt_frame_len is below that, the subtraction wraps as an unsigned value to
a huge length. The memcpy then runs far past the kzalloc'd buffer. A
malicious or malfunctioning AP can make the frame short during the
external SAE auth exchange, so this is a remotely triggered heap overflow.

Reject frames shorter than the management header offset before the copy.

Weakness: CWE-191 (Integer Underflow (Wrap or Wraparound))

## Which versions are affected by CVE-2026-72003?


## How do I fix CVE-2026-72003?

Apply the vendor's patch.

## Is CVE-2026-72003 being exploited?

There is no known exploitation of CVE-2026-72003 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72003 and fix it if it is affected.

What it is: CVE-2026-72003 is a high-severity memory corruption vulnerability in Linux, published on 15 Aug 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-2026-72003 in the wild and no public exploit code.

Affected product: Linux. 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-2026-72003/ (Markdown: https://insights.sbomify.com/CVE-2026-72003/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72003
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72003
- OSV: https://osv.dev/vulnerability/CVE-2026-72003

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72003/
Summaries are generated and may contain mistakes; the official description above is the record.