CVE-2026-6046 Plugin bot username conflict allows user account to be used as bot identity in Mattermost Server

Mattermost versions 11.6.x = 11.6.1, 11.5.x = 11.5.4, 10.11.x = 10.11.15, 10.11.x = 10.11.16 fail to validate that a username returned during bot registration belongs to a bot account, which allows an unprivileged attacker to intercept private messages sent by plugins via direct message channels ...

PT-2026-48936

Mattermost versions 11.6.x = 11.6.1, 11.5.x = 11.5.4, 10.11.x = 10.11.15, 10.11.x = 10.11.16 fail to validate that a username returned during bot registration belongs to a bot account, which allows an unprivileged attacker to intercept private messages sent by plugins via direct message channels ...

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...

Improper Validation of Specified Type of Input

Overview Affected versions of this package are vulnerable to Improper Validation of Specified Type of Input due to the improper validation of plugin bot identity. An attacker can cause users to add reactions to arbitrary GitHub objects by sending crafted notification posts. Remediation Upgrade...

Mattermost 安全漏洞

Mattermost is an open source collaboration platform from Mattermost, Inc. in the United States. Mattermost suffers from a security vulnerability that stems from not verifying the identity of a plugin bot in a reaction forward, which could lead to the hijacking of the GitHub reaction function via...