CVE-2026-2458

Unauthorized channel enumeration in private teams after member removal

State: Published
Severity: 4.3 Medium
Published: Mar 16, 2026
Updated: Mar 16, 2026
Reserved: Feb 13, 2026

Description

Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to properly validate team membership when searching channels which allows a removed team member to enumerate all public channels within a private team via the channel search API endpoint.. Mattermost Advisory ID: MMSA-2025-00568

Scores

CVSS	Score	Vector	Source
3.1	4.3 Medium	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N	Mattermost

Weaknesses

CWE-862 Missing Authorization

Affected Products

Product	Versions
MattermostMattermost	11.3.0 through 11.3.0Affected 11.2.0 through 11.2.2Affected 10.11.0 through 10.11.10Affected 11.4.0Not affected 11.3.1Not affected 11.2.3Not affected 10.11.11Not affected

References

MMSA-2025-00568vendor-advisory

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