Auth bypass in Mattermost
CVE-2026-0998
Mattermost versions 11.1.x <= 11.1.2, 10.11.x <= 10.11.9, 11.2.x <= 11.2.1 and Mattermost Plugin Zoom versions <=1.11.0 fail to validate user identity and post ownership in the {{/api/v1/askPMI}} endpoint which allows unauthorized users to start Zoom meetings as any user and overwrite arbitrary posts via direct API calls with manipulated user IDs and post data.. Mattermost Advisory ID: MMSA-2025-00534
Vulnerability class: Broken Access Control
EPSS: 0.002 (4.9th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N.
Affected products
- Mattermost — versions 11.1.0, 10.11.0, 11.2.0
- Mattermost Mattermost_server
- Mattermost Zoom
Weakness classification (CWE)
References
- responsibledisclosure@mattermost.com (vendor-advisory, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-0998?
- CVE-2026-0998 is a medium-severity vulnerability in Mattermost, classified under Missing Authorization. CVSS score: 4.3/10. Published 2026-02-16.
- How severe is CVE-2026-0998?
- Medium severity. CVSS v3 base score is 4.3 out of 10.