CVE-2025-12689

DoS in Calls plugin via malformed UTF-8 in WebSocket request

Published Dec 17, 2025 CVSS 3.1 · 6.5 Medium EPSS < 1% KEV · Not listed
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.

Remediation

Vendor Solution

Update Mattermost to versions 11.1.0, 11.0.5, 10.12.3, 10.11.7 or higher.

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-j5vq-62gr-8v3r Mattermost fails to check Websocket request for proper UTF-8 format potentially crashing Calls plug-in
References
History
Type Values Removed Values Added
First Time appeared Mattermost mattermost Server
CPEs cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
Vendors & Products Mattermost mattermost Server
Type Values Removed Values Added
First Time appeared Mattermost
Mattermost mattermost
Vendors & Products Mattermost
Mattermost mattermost
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
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.
Title DoS in Calls plugin via malformed UTF-8 in WebSocket request
Weaknesses CWE-1287
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
Mattermost
Published
Updated
Dec 17, 2025, 7:29 PM
Reserved
Nov 4, 2025, 10:06 AM
Status
Analyzed
Published
Dec 17, 2025, 7:16 PM
Modified
Oct 13, 2026, 11:10 AM