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.
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
Fixes

Solution

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


Workaround

No workaround given by the vendor.

References
History

Mon, 29 Dec 2025 18:45:00 +0000

Type Values Removed Values Added
First Time appeared Mattermost mattermost Server
CPEs cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
Vendors & Products Mattermost mattermost Server

Thu, 18 Dec 2025 10:00:00 +0000

Type Values Removed Values Added
First Time appeared Mattermost
Mattermost mattermost
Vendors & Products Mattermost
Mattermost mattermost

Wed, 17 Dec 2025 20:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

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


Wed, 17 Dec 2025 18:30:00 +0000

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'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: Mattermost

Published:

Updated: 2025-12-17T19:29:54.734Z

Reserved: 2025-11-04T10:06:23.912Z

Link: CVE-2025-12689

cve-icon Vulnrichment

Updated: 2025-12-17T18:52:42.809Z

cve-icon NVD

Status : Analyzed

Published: 2025-12-17T19:16:00.537

Modified: 2025-12-29T18:44:33.540

Link: CVE-2025-12689

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2025-12-18T09:57:20Z

Weaknesses