CVE-2025-9076

Mattermost Server exposes sensitive user credentials during shared channel membership synchronization

State: Published
Severity: 6.5 Medium
Published: Sep 15, 2025
Updated: Sep 15, 2025
Reserved: Aug 15, 2025

Description

Mattermost versions 10.10.x <= 10.10.1 fail to properly sanitize user data during shared channel membership synchronization, which allows malicious or compromised remote clusters to access sensitive user information via unsanitized user objects. This vulnerability affects Mattermost Server instances with shared channels enabled.

Scores

CVSS	Score	Vector	Source
3.1	6.5 Medium	CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N	Mattermost

Weaknesses

CWE-862 Missing Authorization

Affected Products

Product	Versions
MattermostMattermost	10.10.0 through 10.10.1Affected 10.11.0Not affected 10.10.2Not affected

References

https://mattermost.com/security-updates

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