CVE-2026-21386 (GCVE-0-2026-21386)
Vulnerability from cvelistv5 – Published: 2026-03-16 14:51 – Updated: 2026-03-16 18:39
VLAI
EPSS
VEX
Title
Private channel enumeration via /mute slash command
Summary
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
Severity
4.3 (Medium)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-03-16 18:39 UTC
CWE
- CWE-203 - Observable Discrepancy
Assigner
Mattermost
CNA
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
11.3.0 , ≤ 11.3.0
(semver)
Affected: 11.2.0 , ≤ 11.2.2 (semver) Affected: 10.11.0 , ≤ 10.11.10 (semver) Unaffected: 11.4.0 Unaffected: 11.3.1 Unaffected: 11.2.3 Unaffected: 10.11.11 |
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Browse all ATT&CK techniques and the vulnerabilities related to each.
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