Vulnerability · Published Dec 17, 2025 · Assigned by Mattermost
CVE-2025-12689DoS in Calls plugin via malformed UTF-8 in WebSocket request
Medium 6.5
In plain English
A medium-severity security flaw in Mattermost from Mattermost. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 21% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)6.5Medium
Exploit odds (30 days)0.3%top 78.6% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Go | github.com/mattermost/mattermost-plugin-calls | 1.11.0 | GHSA-j5vq-62gr-8v3r |
| Go | github.com/mattermost/mattermost-plugin-calls | 1.11.0 | GO-2025-4255 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Mattermost | Mattermost | 11.0.0 – through 11.0.410.12.0 – through 10.12.210.11.0 – through 10.11.6 |
Weakness: CWE-1287 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H