Improper Authentication

Mattermost is vulnerable to improper authentication. The vulnerability is due to failure to validate plugin bot identity in reaction forwarding, which allows an attacker to hijack the GitHub reaction feature and make users add reactions to arbitrary GitHub objects via crafted notification posts...

CVE-2025-13352: Improper Validation of Specified Type of Input

Mattermost versions 10.11.x = 10.11.6 and Mattermost GitHub plugin versions =2.4.0 fail to validate plugin bot identity in reaction forwarding which allows attackers to hijack the GitHub reaction feature to make users add reactions to arbitrary GitHub objects via crafted notification posts...