CVE-2025-12689

Name: CVE-2025-12689
Creator: NVD / NIST
Published: 2025-12-17T19:16:00.537+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 0.24%

Last modified Jun 17, 2026

CVE-2025-12689 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. Mattermost versions 11.0.x <= 11.0.4, 10.12.x <= 10.12.2, 10.11.x <= 10.11.6 fail to check WebSocket request field for proper UTF-8 format, which allows attacker to crash Calls plug-in via sending malformed request.. EPSS estimates a 0.24% chance of exploitation in the next 30 days.

Description

Mattermost versions 11.0.x <= 11.0.4, 10.12.x <= 10.12.2, 10.11.x <= 10.11.6 fail to check WebSocket request field for proper UTF-8 format, which allows attacker to crash Calls plug-in via sending malformed request.

Metrics

CVSS 3.1

6.5/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS Probability

0.24%

15.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-1287

Affected Software

Vendor	Product	Versions
Mattermost	Mattermost Server	>= 10.11.0, < 10.11.7
Mattermost	Mattermost Server	>= 10.12.0, < 10.12.3
Mattermost	Mattermost Server	>= 11.0.0, < 11.0.5

References

https://mattermost.com/security-updatesVendor Advisory

Timeline

Published: Dec 17, 2025
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2025-12689?

How severe is CVE-2025-12689?

CVE-2025-12689 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 0.24% probability of exploitation in the next 30 days.

How do I fix CVE-2025-12689?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2025-12689?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST