CVE-2026-86348: Mattermost

Medium severity, CVSS 4.3. EPSS: 0.4% chance of exploitation in the next 30 days.

Mattermost versions <=11.9 11.0.9 11.4.8 11.7.7 10.22.11.0 fail to recover from handler panics, which allows an authenticated user to crash the plugin via a post-action request with an unexpected field type.. Mattermost Advisory ID: MMSA-2026-00701

Affected products

• Mattermost Mattermost

Published 2026-09-14. Last modified 2026-09-16.