Mattermost Server

Mattermost versions 9.5.x <= 9.5.3, 9.7.x <= 9.7.1 and 8.1.x <= 8.1.12 fail to perform a proper authorization check in the /api/v4/groups/<group-id>/channels/<channel-id>/link endpoint which allows a user to learn the members of an AD/LDAP group that is linked to a team by adding the group to a channel, even if the user has no access to the team.Show less

Mattermost versions 9.5.x <= 9.5.3, 9.6.x <= 9.6.1, 8.1.x <= 8.1.12 fail to enforce proper access controls for channel and team membership when linking a playbook run to a channel which allows members to link their runs to private channels they were not members of.Show less

Mattermost versions 9.5.x <= 9.5.3, 9.7.x <= 9.7.1, 9.6.x <= 9.6.1, 8.1.x <= 8.1.12 fail to enforce proper access control which allows a user to run a slash command in a channel they are not a member of via linking a playbook run to that channel and running a slash command as a playbook task command.Show less

Mattermost versions 9.6.0, 9.5.x before 9.5.3, and 8.1.x before 8.1.12 fail to fully validate role changes, which allows an attacker authenticated as a team admin to promote guests to team admins via crafted HTTP requests. Show less

Mattermost versions 8.1.x before 8.1.12, 9.6.x before 9.6.1, 9.5.x before 9.5.3, 9.4.x before 9.4.5 fail to limit the number of active sessions, which allows an authenticated attacker to crash the server via repeated requests to the getSessions API after flooding the sessions table. Show less

Mattermost versions 9.6.0, 9.5.x before 9.5.3, 9.4.x before 9.4.5, and 8.1.x before 8.1.12 fail to handle JSON parsing errors in custom status values, which allows an authenticated attacker to crash other users' web clients via a malformed custom status. Show less

Mattermost versions 9.6.x <= 9.6.0, 9.5.x <= 9.5.2, 9.4.x <= 9.4.4 and 8.1.x <= 8.1.11 fail to remove detailed error messages in API requests even if the developer mode is off which allows an attacker to get information about the server such as the full path were files are stored Show less

Mattermost versions 8.1.x <= 8.1.10, 9.6.x <= 9.6.0, 9.5.x <= 9.5.2 and 8.1.x <= 8.1.11 fail to limit the size of a request path that includes user inputs which allows an attacker to cause excessive resource consumption, possibly leading to a DoS via sending large request paths Show less

Mattermost versions 8.1.x before 8.1.11, 9.3.x before 9.3.3, 9.4.x before 9.4.4, and 9.5.x before 9.5.2 fail to authenticate the source of certain types of post actions, allowing an authenticated attacker to create posts as other users via a crafted post action. Show less

Improper Access Control in Mattermost Server versions 9.5.x before 9.5.2, 9.4.x before 9.4.4, 9.3.x before 9.3.3, 8.1.x before 8.1.11 lacked proper access control in the `/api/v4/users/me/teams` endpoint allowing a team admin to get the invite ID of their team, thus allowing them to invite users, even if the "Add Members" permission was explicitly removed from team admins. Show less

Mattermost Server versions 9.5.x before 9.5.2, 9.4.x before 9.4.4, 9.3.x before 9.3.3, 8.1.x before 8.1.11 don't limit the number of user preferences which allows an attacker to send a large number of user preferences potentially causing denial of service. Show less

Mattermost versions 8.1.x before 8.1.10, 9.2.x before 9.2.6, 9.3.x before 9.3.2, and 9.4.x before 9.4.3 fail to correctly verify account ownership when switching from email to SAML authentication, allowing an authenticated attacker to take over other user accounts via a crafted switch request under specific conditions. Show less

Mattermost versions 8.1.x before 8.1.10, 9.2.x before 9.2.6, 9.3.x before 9.3.2, and 9.4.x before 9.4.3 fail to limit the number of @-mentions processed per message, allowing an authenticated attacker to crash the client applications of other users via large, crafted messages. Show less

Mattermost Jira plugin versions shipped with Mattermost versions 8.1.x before 8.1.10, 9.2.x before 9.2.6, 9.3.x before 9.3.2, and 9.4.x before 9.4.3 fail to escape user-controlled outputs when generating HTML pages, which allows an attacker to perform reflected cross-site scripting attacks against the users of the Mattermost server. Show less

Mattermost versions 8.1.x before 8.1.9, 9.2.x before 9.2.5, 9.3.0, and 9.4.x before 9.4.2 fail to limit the number of role names requested from the API, allowing an authenticated attacker to cause the server to run out of memory and crash by issuing an unusually large HTTP request. Show less

Mattermost version 8.1.x before 8.1.9 fails to sanitize data associated with permalinks when a plugin updates an ephemeral post, allowing an authenticated attacker who can control the ephemeral post update to access individual posts' contents in channels they are not a member of. Show less