An issue was discovered in Mattermost Server before 3.8.2, 3.7.5, and 3.6.7. An external link can occur on an error page even if it is not on an allowlist.
An issue was discovered in Mattermost Server before 3.8.2, 3.7.5, and 3.6.7. API endpoint access control does not honor an integration permission restriction.
An issue was discovered in Mattermost Server before 3.3.0. An attacker could use the WebSocket feature to send pop-up messages to users or change a post's appearance.
An issue was discovered in Mattermost Server before 4.2.0, 4.1.1, and 4.0.5. It allows attackers to obtain sensitive information (user statuses) via a REST API version 4 endpoint.