Mattermost Apps Framework fails to verify that a secret provided in the incoming webhook request allowing an attacker to modify the contents of the post sent by the Apps.

Mattermost fails to verify if the requestor is a sysadmin or not, before allowing install requests to the Apps allowing a regular user send install requests to the Apps.

Mattermost fails to properly check the permissions when executing commands allowing a member with no permissions to post a message in a channel to actually post it by executing channel commands.

Mattermost fails to check channel membership when accessing message threads, allowing an attacker to access arbitrary posts by using the message threads API.

Mattermost fails to check if an admin user account active after an oauth2 flow is started, allowing an attacker with admin privileges to retain persistent access to Mattermost by obtaining an oauth2 access token while the attacker's account is deactivated.

Mattermost fails to sanitize ephemeral error messages, allowing an attacker to obtain arbitrary message contents by a specially crafted /groupmsg command.

Mattermost fails to unescape Markdown strings in a memory-efficient way, allowing an attacker to cause a Denial of Service by sending a message containing a large number of escaped characters.

Mattermost fails to properly truncate the postgres error log message of a search query failure allowing an attacker to cause the creation of large log files which can result in Denial of Service