CVE-2025-12421: Incorrect Implementation of Authentication Algorithm

Mattermost versions 11.0.x = 11.0.2, 10.12.x = 10.12.1, 10.11.x = 10.11.4, 10.5.x = 10.5.12 fail to to verify that the token used during the code exchange originates from the same authentication flow, which allows an authenticated user to perform account takeover via a specially crafted email...