CVE-2026-21386

MEDIUM EPSS 8.2%
Published Mar 16, 20263mo ago · Modified Jun 17, 20262w ago
4.3 CVSS 3.1
Medium
Find Similar
Published Mar 16, 2026 3mo ago
Last Modified Jun 17, 2026 2w ago

Description

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

CVSS Details

Base Score
4.3
Exploitability
2.8
Impact
1.4
Vector string
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

Threat Intelligence

EPSS Exploit Probability
8.2% percentile
Exploit & Patch Status
No Known Exploit
No Patch Available

Weaknesses 1

CWE-203

Affected Products 3

VendorProductVersionRange
mattermostmattermost_server*≥10.11.0  –  <10.11.11
mattermostmattermost_server*≥11.2.0  –  <11.2.3
mattermostmattermost_server*≥11.3.0  –  <11.3.1

References 1

  • mattermost.com https://mattermost.com/security-updates
    Vendor Advisory

Remediation

No remediation data recorded yet

Check vendor advisories and the NVD entry for patch availability.