Vulnerability in Mattermost
CVE-2026-9571
Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to invalidate OAuth refresh tokens upon user account deactivation, which allows a deactivated user or an attacker in possession of a valid refresh token to ob…
CVSS v3 metric
CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:N.
Affected products
- Mattermost — versions 11.7.0, 11.6.0, 10.11.0
- Mattermost Mattermost_server
Weakness classification (CWE)
References
- responsibledisclosure@mattermost.com (vendor-advisory, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-9571?
- CVE-2026-9571 is a medium-severity vulnerability in Mattermost, classified under Authentication Bypass by Primary Weakness. CVSS score: 5.9/10. Published 2026-07-13.
- How severe is CVE-2026-9571?
- Medium severity. CVSS v3 base score is 5.9 out of 10.