Moole Vulnerability Database

Find real vulnerabilities before they ship

Medium

CVE-2026-21386

Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to use consistent error responses when handling the /mute command which allows an authenticated team member to enumerate private channels they are not authorized to know about via differing error messages for nonexistent versus private channels. Mattermost Advisory ID: MMSA-2026-00588

VectorNETWORK

PublishedMar 16, 2026, 15:16

Published Byresponsibledisclosure@mattermost.com

Base Score

Score4.3

Affected Versions

Package (Ecosystem)IntroducedFixedLimit

github.com/mattermost/mattermost/server/v8(Go)08.0.0-20260130144323-5bb5261c72faN/A

github.com/mattermost/mattermost-server(Go)05.3.2-0.20260130144323-5bb5261c72faN/A

github.com/mattermost/mattermost-server(Go)10.11.0-rc110.11.11N/A

github.com/mattermost/mattermost-server(Go)11.2.0-rc111.2.3N/A

github.com/mattermost/mattermost-server(Go)11.3.0-rc111.3.1N/A

References

https://mattermost.com/security-updates

Weakness Type

CWE-203

CVSS Metrics

Base Score

4.3

Vector String

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

Base SeverityMedium

Version

3.1

Attack Vector (AV)

NETWORK