Vulnerability in Mattermost
CVE-2026-4635
Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to archive the channel before removing persistent notifications which allows authenticated user to crash the server via timing the creation…
Vulnerability class: Race Condition
EPSS: 0.000 (13.2th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
Affected products
- Mattermost — versions 11.6.0, 11.5.0, 11.4.0
- Mattermost Mattermost_server
Weakness classification (CWE)
References
- responsibledisclosure@mattermost.com (vendor-advisory, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-4635?
- CVE-2026-4635 is a medium-severity vulnerability in Mattermost, classified under Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition). CVSS score: 6.5/10. Published 2026-05-22.
- How severe is CVE-2026-4635?
- Medium severity. CVSS v3 base score is 6.5 out of 10.