CVE-2025-20621 Information

Description

Mattermost versions 10.2.x <= 10.2.0 9.11.x <= 9.11.5 10.0.x <= 10.0.3 10.1.x <= 10.1.3 fail to properly handle posts with attachments containing fields that cannot be cast to a String which allows an attacker to cause the webapp to crash via creating and sending such a post to a channel.

Reference

https://mattermost.com/security-updates