CVE-2026-2458

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

Affected packages (6)

• Go/github.com/mattermost/mattermost-serverfrom 0, < 5.3.2-0.20260113182106-a18b80ba4c32
• Go/github.com/mattermost/mattermost-server>= 10.11.0-rc1+incompatible, < 10.11.11+incompatible, >= 11.2.0-rc1+incompatible, < 11.2.3+incompatible, >= 11.3.0-rc1+incompatible, < 11.3.1+incompatible
• Go/github.com/mattermost/mattermost-server/v5from 0
• Go/github.com/mattermost/mattermost-server/v6from 0
• Go/github.com/mattermost/mattermost/server/v8from 0, < 8.0.0-20260113182106-a18b80ba4c32
• Go/github.com/mattermost/mattermost/server/v8from 0, < 8.0.0-20260113182106-a18b80ba4c32

CVSS scores

References (5)

• ADVISORYhttps://github.com/advisories/GHSA-679f-wmrg-qf57
• ADVISORYhttps://nvd.nist.gov/vuln/detail/CVE-2026-2458
• PATCHhttps://github.com/mattermost/mattermost
• WEBhttps://github.com/mattermost/mattermost/commit/a18b80ba4c324b74b3d47951c33957305af4a099
• WEBhttps://mattermost.com/security-updates