Mattermost vulnerabilities

Mattermost fails to restrict which parameters' values it takes from the request during signup, allowing an attacker to register users as inactive. This blocks them from later accessing Mattermost without the system admin activating their accounts.

Mattermost fails to sanitize post metadata during audit logging, resulting in permalinks contents being logged.

Mattermost fails to properly validate the requesting user permissions when updating a system admin, allowing a user manager to update a system admin's details such as email, first name and last name.

Mattermost fails to check if the requesting user is a guest, allowing guests to view, join, edit, export, and archive public playbooks.

Mattermost fails to delete the attachments when deleting a message in a thread, allowing a simple user to still access and download the attachment of a deleted message.

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.

Mattermost fails to properly validate markdown, allowing an attacker to crash the server via a specially crafted markdown input.

Mattermost fails to invalidate previously generated password reset tokens when a new reset token is created.

Mattermost fails to properly show information in the UI, allowing a system admin to modify a board state. This allows any user with a valid sharing link to join the board with editor access, without the UI showing the updated permissions.

Mattermost fails to disable public Boards after the 'Enable Publicly-Shared Boards' configuration option is disabled, resulting in previously-shared public Boards to remain accessible.

Mattermost fails to properly check the authorization of POST /api/v4/teams when passing a team override scheme ID in the request. This allows an authenticated attacker with knowledge of a Team Override Scheme ID to create a new team with said team override scheme.

Mattermost fails to verify channel membership when linking a board to a channel, allowing a low-privileged authenticated user to link a Board to a private channel they don't have access to.

Mattermost fails to properly validate the origin of a websocket connection, allowing a MITM attacker to access the websocket APIs.

Mattermost fails to properly restrict requests to localhost/intranet during the interactive dialog, which could allow an attacker to perform a limited blind SSRF.