Mattermost Server

A race condition in Mattermost versions 8.1.x before 8.1.9, and 9.4.x before 9.4.2 allows an authenticated attacker to gain unauthorized access to individual posts' contents via carefully timed post creation while another user deletes posts. Show less

Mattermost versions 8.1.x before 8.1.9, 9.2.x before 9.2.5, and 9.3.0 fail to sanitize the metadata on posts containing permalinks under specific conditions, which allows an authenticated attacker to access the contents of individual posts in channels they are not a member of. Show less

Mattermost fails to check the "invite_guest" permission when inviting guests of other teams to a team, allowing a member with permissions to add other members but not to add guests to add a guest to a team as long as the guest was already a guest in another team of the server Show less

Mattermost fails to properly validate the length of the emoji value in the custom user status, allowing an attacker to send multiple times a very long string as an emoji value causing high resource consumption and possibly crashing the server. Show less

Mattermost fails to properly restrict the access of files attached to posts in an archived channel, resulting in members being able to access files of archived channels even if the “Allow users to view archived channels” option is disabled. Show less

Mattermost fails to check if compliance export is enabled when fetching posts of public channels allowing a user that is not a member of the public channel to fetch the posts, which will not be audited in the compliance export.  Show less

Mattermost fails to check if a custom emoji reaction exists when sending it to a post and to limit the amount of custom emojis allowed to be added in a post, allowing an attacker sending a huge amount of non-existent custom emojis in a post to crash the mobile app of a user seeing the post and to crash the server due to overloading when clients attempt to retrive the aforementioned post.  Show less

Mattermost Jira Plugin handling subscriptions fails to check the security level of an incoming issue or limit it based on the user who created the subscription resulting in registered users on Jira being able to create webhooks that give them access to all Jira issues. Show less

Mattermost fails to scope the WebSocket response around notified users to a each user separately resulting in the WebSocket broadcasting the information about who was notified about a post to everyone else in the channel. Show less

Mattermost fails to properly verify the permissions needed for viewing archived public channels,  allowing a member of one team to get details about the archived public channels of another team via the GET /api/v4/teams/<team-id>/channels/deleted endpoint. Show less

Mattermost fails to perform correct authorization checks when creating a playbook action, allowing users without access to the playbook to create playbook actions. If the playbook action created is to post a message in a channel based on specific keywords in a post, some playbook information, like the name, can be leaked.  Show less

Mattermost fails to validate team membership when a user attempts to access a playbook, allowing a user with permissions to a playbook but no permissions to the team the playbook is on to access and modify the playbook. This can happen if the user was once a member of the team, got permissions to the playbook and was then removed from the team.  Show less

Mattermost fails to handle a null request body in the /add endpoint, allowing a simple member to send a request with null request body to that endpoint and make it crash. After a few repetitions, the plugin is disabled.  Show less