CVE-2026-28735

Mattermost versions 10.11.x up to 10.11.14, 11.4.x up to 11.4.4, 11.5.x up to 11.5.3, and 11.6.x up to 11.6.0 fail to validate the OAuth token scope on the callback, enabling an authenticated Mattermost user to gain access to private repositories by modifying the scope parameter in the GitHub aut...