SUSE CVE-2026-27656

Mattermost versions 11.4.x = 11.4.0, 11.3.x = 11.3.1, 11.2.x = 11.2.3, 10.11.x = 10.11.11 fail to properly validate user identity in the OpenID IsSameUser comparison logic, which allows an attacker to take over arbitrary user accounts via an overly permissive substring matching flaw in the user...

Incorrect Implementation of Authentication Algorithm

Overview github.com/mattermost/mattermost-server is an open source Slack-alternative in Golang and React. Affected versions of this package are vulnerable to Incorrect Implementation of Authentication Algorithm in the IsSameUser function. An attacker can gain unauthorized access to arbitrary user...