Unrated
Private channel enumeration via /mute slash command
CVE-2026-21386
First seen on SecPulse
Original description The description as published by the source.
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
Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV
References
- advisory github.com
- advisory mattermost.com
- advisory nvd.nist.gov