CVE-2025-11777

Cross-team channel membership access

State: Published
Severity: 3.1 Low
Published: Nov 13, 2025
Updated: Nov 13, 2025
Reserved: Oct 15, 2025

Description

Mattermost versions 10.11.x <= 10.11.3, 10.5.x <= 10.5.11 fail to properly validate team membership permissions in the Add Channel Member API which allows users from one team to access user metadata and channel membership information from other teams via the API endpoint

Scores

CVSS	Score	Vector	Source
3.1	3.1 Low	CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N	Mattermost

Weaknesses

CWE-863 Incorrect Authorization

Affected Products

Product	Versions
MattermostMattermost	10.11.0 through 10.11.3Affected 10.5.0 through 10.5.11Affected 11.0.0Not affected 10.11.4Not affected 10.5.12Not affected

References

https://mattermost.com/security-updates

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