CyberSecBulletin
CVE-2026-31679NVD status: Modified

In the Linux kernel, the following vulnerability has been resolved: openvswitch: validate MPLS…

Published Updated By the CyberSecBulletin desk

CVE-2026-31679 is a high-severity improper input validation vulnerability in Linux, with a CVSS 3.1 base score of 7.1 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 68f32ef0683c8d1c05cd2e4f16818fa63ff59c6f, 4cae986225f8b8679ad86b924918e7d75a96aa61, 8ed7b9930cbc3bc71f868fa79a68700ac88d586a as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.16% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to 68f32ef0683c8d1c05cd2e4f16818fa63ff59c6f or 4cae986225f8b8679ad86b924918e7d75a96aa61 or 8ed7b9930cbc3bc71f868fa79a68700ac88d586a or c1f97152df8dfb17e855ddf0fc409b7bd13e9700, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.10.253 or 5.15.203 or 6.1.168 or 6.6.131, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxfbdcdd78da7c95f1b970d371e1b23cbd3aa990f3 up to, but not including, 68f32ef0683c8d1c05cd2e4f16818fa63ff59c6f; fbdcdd78da7c95f1b970d371e1b23cbd3aa990f3 up to, but not including, 4cae986225f8b8679ad86b924918e7d75a96aa61; fbdcdd78da7c95f1b970d371e1b23cbd3aa990f3 up to, but not including, 8ed7b9930cbc3bc71f868fa79a68700ac88d586a; fbdcdd78da7c95f1b970d371e1b23cbd3aa990f3 up to, but not including, c1f97152df8dfb17e855ddf0fc409b7bd13e9700; fbdcdd78da7c95f1b970d371e1b23cbd3aa990f3 up to, but not including, 98de18d327ef8cbbb704980e359e4872d8c28997; fbdcdd78da7c95f1b970d371e1b23cbd3aa990f3 up to, but not including, bd50c7484c3bb34097571c1334174fb8b7408036; fbdcdd78da7c95f1b970d371e1b23cbd3aa990f3 up to, but not including, 2ca33b88a79ca42f017ae0f7011280325655438e; fbdcdd78da7c95f1b970d371e1b23cbd3aa990f3 up to, but not including, 546b68ac893595877ffbd7751e5c55fd1c43ede6; and 1 more ranges68f32ef0683c8d1c05cd2e4f16818fa63ff59c6f, 4cae986225f8b8679ad86b924918e7d75a96aa61, 8ed7b9930cbc3bc71f868fa79a68700ac88d586a, c1f97152df8dfb17e855ddf0fc409b7bd13e9700, 98de18d327ef8cbbb704980e359e4872d8c28997, bd50c7484c3bb34097571c1334174fb8b7408036
LinuxLinux Kernel5.5 up to, but not including, 5.10.253; 5.11 up to, but not including, 5.15.203; 5.16 up to, but not including, 6.1.168; 6.2 up to, but not including, 6.6.131; 6.7 up to, but not including, 6.12.80; 6.13 up to, but not including, 6.18.21; 6.19 up to, but not including, 6.19.11; 7.05.10.253, 5.15.203, 6.1.168, 6.6.131, 6.12.80, 6.18.21

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H. Scored by CNA.

Official 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.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Input Validation

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

How developers prevent this class of flaw

  • Consider using language-theoretic security (LangSec) techniques that characterize inputs using a formal language and build recognizers for that language. This effectively requires parsing to be a distinct layer that effectively enforces a boundary between raw input and internal data representations, instead of allowing parser code to be scattered throughout the program, where it could be subject to errors or inconsistencies that create weaknesses.
  • Use an input validation framework such as Struts or the OWASP ESAPI Validation API. Note that using a framework does not automatically address all input validation problems; be mindful of weaknesses that could arise from misusing the framework itself (CWE-1173).
  • Understand all the potential areas where untrusted inputs can enter the product, including but not limited to: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls.

More Improper Input Validation vulnerabilities (CWE-20)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Improper Input Validation vulnerabilities

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