CVE-2026-21386
Private channel enumeration via /mute slash command
CVSS Score
4.3
EPSS Score
0.0%
EPSS Percentile
0th
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
| CWE | CWE-203 |
| Vendor | mattermost |
| Product | mattermost |
| Published | Mar 16, 2026 |
| Last Updated | Mar 16, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None
Affected Versions
Mattermost / Mattermost
11.3.0 ≤ 11.3.0 11.2.0 ≤ 11.2.2 10.11.0 ≤ 10.11.10
Credits
winfunc