What is CVE-2025-12689?

CVE-2025-12689 is a medium-severity vulnerability in Mattermost, classified under CWE-1287. CVSS score: 6.5/10. Published 2025-12-17.

How severe is CVE-2025-12689?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Vulnerability in Mattermost

CVE-2025-12689

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: 0.003 (16.4th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

Affected products

Mattermost — versions 11.0.0, 10.12.0, 10.11.0
Mattermost Mattermost_server

Weakness classification (CWE)

CWE-1287

References

responsibledisclosure@mattermost.com (Vendor Advisory)

Frequently asked questions

What is CVE-2025-12689?: CVE-2025-12689 is a medium-severity vulnerability in Mattermost, classified under CWE-1287. CVSS score: 6.5/10. Published 2025-12-17.
How severe is CVE-2025-12689?: Medium severity. CVSS v3 base score is 6.5 out of 10.