# CVE-2026-74409: wifi: rtw89: add bounds check on firmware mac_id in link lookup

> A missing bounds check in the rtw89 WiFi driver allows out-of-bounds array access via firmware-provided mac_id, potentially causing crashes or data leaks.

- **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:** 16 Oct 2026
- **Also known as:** BELL-CVE-2026-74409, DEBIAN-CVE-2026-74409, GHSA-58gw-vjvj-7rmp, UBUNTU-CVE-2026-74409

## What is CVE-2026-74409?

CVE-2026-74409 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: rtw89: add bounds check on firmware mac_id in link lookup

The mac_id field in RX descriptors is 8 bits wide (0-255), but
assoc_link_on_macid[] has only RTW89_MAX_MAC_ID_NUM (128) entries.
While the driver currently assigns mac_id values below 128, the
descriptor value comes from firmware and is not validated before use
as an array index. Add a defensive bounds check in
rtw89_assoc_link_rcu_dereference() to guard against out-of-range
firmware values.

## Which versions are affected by CVE-2026-74409?


## How do I fix CVE-2026-74409?

Apply the vendor's patch.

## Is CVE-2026-74409 being exploited?

There is no known exploitation of CVE-2026-74409 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74409 and fix it if it is affected.

What it is: CVE-2026-74409 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-2026-74409 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-2026-74409/ (Markdown: https://insights.sbomify.com/CVE-2026-74409/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74409
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74409
- OSV: https://osv.dev/vulnerability/CVE-2026-74409

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74409/
Summaries are generated and may contain mistakes; the official description above is the record.