Playbook Plugin Crash via Run Checklist

Mattermost fails to to check the length when setting the title in a run checklist in Playbooks, allowing an attacker to send a specially crafted request and crash the Playbooks plugin

Incorrect Authorization leads to Channel Member Count Leak

Mattermost fails to check the required permissions in the POST /api/v4/channels/stats/member_count API resulting in channel member counts being leaked to a user without permissions.

Missing authorization allows users to access arbitrary security levels on Jira through webhooks (Jira Plugin)

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.

CSRF issue allows disconnecting a user's Jira connection through a simple post message (Jira Plugin)

Mattermost Jira Plugin fails to protect against logout CSRF allowing an attacker to post a specially crafted message that would disconnect a user's Jira connection in Mattermost only by viewing the message.

Denial of service in mattermost mobile apps and server via emoji reactions

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. 

Mattermost version 8.1.6 and earlier fails to sanitize channel mention data in posts, which allows an attacker to inject markup in the web client.

Client side path traversal due to lack of route parameters validation

Mattermost webapp fails to validate route parameters in/<TEAM_NAME>/channels/<CHANNEL_NAME> allowing an attacker to perform a client-side path traversal.

Denial of Service via multiple identical User IDs in /api/v4/users/ids

Mattermost fails to deduplicate input IDs allowing a simple user to cause the application to consume excessive resources and possibly crash by sending a specially crafted request to /api/v4/users/ids with multiple identical IDs.

File Information Leak via IDOR in file_id in Draft Posts

Mattermost fails to properly check the creator of an attached file when adding the file to a draft post, potentially exposing unauthorized file information.

Denial of Service via Opengraph Data Cache

Mattermost fails to enforce a limit for the size of the cache entry for OpenGraph data allowing an attacker to send a specially crafted request to the /api/v4/opengraph filling the cache and turning the server unavailable.

Parameter tampering in the registration resulting in blocked accounts to be created

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.

IDOR when updating the tasks of a private playbook run

Mattermost fails to check whether a user is a guest when updating the tasks of a private playbook run allowing a guest to update the tasks of a private playbook run if they know the run ID.

Todo plugin gets crashed and disabled by member

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. 

Playbook plugin crash via missing interface type assertion

Mattermost fails to validate the type of the "reminder" body request parameter allowing an attacker to crash the Playbook Plugin when updating the status dialog.

Inaccessible Post Information Leak via Run Timeline IDOR

Mattermost fails to perform authorization checks in the /plugins/playbooks/api/v0/runs/add-to-timeline-dialog endpoint of the Playbooks plugin allowing an attacker to get limited information about a post if they know the post ID

Denial of Service via specially crafted gif image

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.

Guest accounts invited and added to channels by Welcomebot plugin

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.

Server crash via a specially crafted markdown input

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

Lack of previous password reset tokens on new token creation

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

Deleted attachments in Boards remain accessible

Mattermost fails to delete card attachments in Boards, allowing an attacker to access deleted attachments.