Mattermost fails to restrict which parameters' values it takes from the request during signup allowing an attacker to register users as inactive, thus blocking them from later accessing Mattermost without the system admin activating their accounts.
Mattermost WelcomeBot plugin fails to to validate the membership status when inviting or adding users to channels allowing guest accounts to be added or invited to channels by default.
Mattermost fails to properly validate a gif image file, allowing an attacker to consume a significant amount of server resources, making the server unresponsive for an extended period of time by linking to specially crafted image file.
When archiving a team, Mattermost fails to sanitize the related Websocket event sent to currently connected clients. This allows the clients to see the name, display name, description, and other data about the archived team.
Mattermost fails to redact from audit logs the user password during user creation and the user password hash in other operations if the experimental audit logging configuration was enabled (ExperimentalAuditSettings section in config).
A reflected cross-site scripting vulnerability in the OAuth flow completion endpoints in Mattermost allows an attacker to send AJAX requests on behalf of the victim via sharing a crafted link with a malicious state parameter.
Mattermost fails to honor the ShowEmailAddress setting when constructing a response to the /api/v4/users/me/teams API endpoint, allowing an attacker with team admin privileges to learn the team owner's email address in the response.
Mattermost fails to honor the ShowEmailAddress setting when constructing a response to the "Regenerate Invite Id" API endpoint, allowing an attacker with team admin privileges to learn the team owner's email address in the response.
Mattermost version 7.1.x and earlier fails to sufficiently process a specifically crafted GIF file when it is uploaded while drafting a post, which allows authenticated users to cause resource exhaustion while processing the file, resulting in server-side Denial of Service.