Mattermost vulnerabilities
We track 66 vulnerabilities in Mattermost products across 10 products. 66 are rated high or critical, and none are known to be exploited. The most recent was published on October 28, 2026.
Latest Mattermost vulnerabilities
- 8.0 High severity
Mattermost: Improper Limitation of a Pathname to a Restricted Directory
Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10 fail to validate the target post ID in the Agents plugin's mention reminder component, which allows an authenticated user who can post in a channel visible to a system administrator to c
- 7.1 High severity
Mattermost: External Control of Assumed-Immutable Web Parameter
Mattermost versions 11.10.x <= 11.10.0, 11.7.x <= 11.7.9, 11.9.x <= 11.9.1, 11.8.x <= 11.8.5 fail to verify the integrity of the SAML RelayState POST parameter which allows an authenticated SAML user to join any team, including invite-only teams, via forging t
- 9.3 Critical severity
Mattermost: URL Redirection to Untrusted Site
Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7 Mattermost failed to validate Dynamic Client Registration redirect URIs by URL component (matching glob patterns against the raw URI string instead) which allows a remote unauthenticated
- 7.1 High severity
Mattermost: Missing Authorization
Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7, 10.11.x <= 10.11.22 fail to validate channel member-management permission during playbook run creation, allowing an authenticated channel member to add an arbitrary user to a restricted
- 8.3 High severity
Mattermost: Incorrect Authorization
Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fail to validate BoardMember.Scheme* fields server-side on insert and archive-import paths which allows a board editor or non-guest team member to grant board admin to arbitrary users
- 7.7 High severity
Mattermost: Insufficiently Protected Credentials
Mattermost Desktop App versions <=6.1 5.5.13.0 fail to restrict the allow list of domains to which NTLM credentials were forwarded to in the Mattermost Desktop App which allows any user on a server without the image proxy enabled to intercept other users crede
- 8.8 High severity
Mattermost: Incorrect Authorization
Mattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15, 10.11.x <= 10.11.16 Mattermost fails to require role-management authorization when setting the scheme_admin flag on group syncable link and patch endpoints, which allows a user with g
- 7.6 High severity
Mattermost: Improper Limitation of a Pathname to a Restricted Directory
Mattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15, 10.11.x <= 10.11.16 Mattermost fails to sanitize FileInfo.Name received from federated peers during shared channel file sync, which allows an attacker who controls a federated server
- 7.2 High severity
Mattermost: Incorrect Authorization
Mattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15, 10.11.x <= 10.11.16 fail to require system-level permission when patching protected default system roles, which allows authenticated users with delegated user-management permissions t
- 7.5 High severity
Mattermost: Memory Allocation with Excessive Size Value
Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to properly validate msgpack-encoded WebSocket frames before memory allocation which allows an unauthenticated remote attacker to crash the server process and ca
- 7.5 High severity
Mattermost: Uncontrolled Resource Consumption
Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to enforce request body size limits on plugin HTTP endpoints which allows an attacker to cause a denial of service via crafted oversized HTTP requests.. Mattermo
- 7.1 High severity
Mattermost: Authorization Bypass Through User-Controlled Key
Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to validate file ownership and access control, which allows an authenticated user to access and download files belonging to other users or teams via crafted Boar
- 9.9 Critical severity
Mattermost: Improper Limitation of a Pathname to a Restricted Directory
Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to check integration URL for path traversal which allows an malicious authenticated user to call an arbitrary API via system admin Mattermost auth token using vi
- 7.6 High severity
Mattermost: Exposure of Sensitive Information to an Unauthorized Actor
Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail to sanitize sensitive configuration fields in the Mattermost Calls plugin which allows an attacker with access to a support packet to obtain TURN server credentials via the plaint
- 8.7 High severity
Mattermost: Exposure of Sensitive Information to an Unauthorized Actor
Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail to sanitize sensitive configuration fields before including them in support packet generation, which allows a Mattermost System Admin or any party with access to a support packet
- 8.1 High severity
Mattermost: Cross-Site Request Forgery
Mattermost versions 10.11.x <= 10.11.12, 11.5.x <= 11.5.0, 11.4.x <= 11.4.2, 11.3.x <= 11.3.2 fail to validate CSRF tokens on an authentication endpoint which allows an attacker to update a user's authentication method via a CSRF attack by tricking a user into
- 8.8 High severity
Mattermost: Missing Authorization
Mattermost Plugin Legal Hold versions <=1.1.4 fail to halt request processing after a failed authorization check in ServeHTTP which allows an authenticated attacker to access, create, download, and delete legal hold data via crafted API requests to the plugin'
- 8.8 High severity
Mattermost: Improper Neutralization of Escape, Meta, or Control Sequences
Mattermost versions 11.2.x <= 11.2.2, 10.11.x <= 10.11.10, 11.4.x <= 11.4.0, 11.3.x <= 11.3.1 fail to sanitize user-controlled post content in the mmctl commands terminal output which allows attackers to manipulate administrator terminals via crafted messages
- 7.5 High severity
Mattermost: Improper Check for Unusual or Exceptional Conditions
Mattermost versions 11.4.x <= 11.4.0, 11.3.x <= 11.3.1, 11.2.x <= 11.2.3, 10.11.x <= 10.11.11 fail to prevent rendering of external SVGs on link embeds which allows unauthenticated users to crash the Mattermost webapp and desktop app via creating an issue or P
- 8.6 High severity
Mattermost: Improper Validation of Specified Type of Input
Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to handle incorrectly reported array lengths which allows malicious user to cause OOM errors and crash the server via sending corrupted msgpack frames within websocket messages to
- 7.5 High severity
Mattermost: Allocation of Resources Without Limits or Throttling
Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to properly handle very long passwords, which allows an attacker to overload the server CPU and memory via executing login attempts with multi-megabyte passwords. Mattermost Advis
- 8.3 High severity
Mattermost: Incorrect Implementation of Authentication Algorithm
Mattermost versions 11.1.x <= 11.1.0, 11.0.x <= 11.0.5, 10.12.x <= 10.12.3, 10.11.x <= 10.11.7 with the Jira plugin enabled and Mattermost Jira plugin versions <=4.4.0 fail to enforce authentication and issue-key path restrictions in the Jira plugin, which all
- 9.9 Critical severity
Mattermost: Incorrect Implementation of Authentication Algorithm
Mattermost versions 11.0.x <= 11.0.2, 10.12.x <= 10.12.1, 10.11.x <= 10.11.4, 10.5.x <= 10.5.12 fail to to verify that the token used during the code exchange originates from the same authentication flow, which allows an authenticated user to perform account t
- 9.9 Critical severity
Mattermost: Incorrect Implementation of Authentication Algorithm
Mattermost versions 10.12.x <= 10.12.1, 10.11.x <= 10.11.4, 10.5.x <= 10.5.12, 11.0.x <= 11.0.3 fail to properly validate OAuth state tokens during OpenID Connect authentication which allows an authenticated attacker with team creation privileges to take over
- 7.5 High severity
Mattermost: Missing Authentication for Critical Functionality
Mattermost versions <11 fail to enforce multi-factor authentication on WebSocket connections which allows unauthenticated users to access sensitive information via WebSocket events
- 8.1 High severity
Mattermost: Missing Authorization
Mattermost versions 10.11.x <= 10.11.1, 10.10.x <= 10.10.2, 10.5.x <= 10.5.10 fail to verify a user has permission to join a Mattermost team using the original invite token which allows any attacked to join any team on a Mattermost server regardless of restric
- 8.1 High severity
Mattermost: Missing Authorization
Mattermost versions 10.11.x <= 10.11.1, 10.10.x <= 10.10.2, 10.5.x <= 10.5.10 fail to verify a user has permission to join a Mattermost team using the original invite token which allows any attacked to join any team on a Mattermost server regardless of restric
- 7.2 High severity
Mattermost: Improper Limitation of a Pathname to a Restricted Directory
Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.10.x <= 10.10.1, 10.9.x <= 10.9.3 fail to validate import directory path configuration which allows admin users to execute arbitrary code via malicious plugin upload to prepackaged p
- 7.5 High severity
Mattermost Confluence Plugin: Improper Validation of Specified Type of Input
Mattermost Confluence Plugin version <1.5.0 fails to handle unexpected request body which allows attackers to crash the plugin via constant hit to create channel subscription endpoint with an invalid request body.
- 7.5 High severity
Mattermost Confluence Plugin: Improper Check for Unusual or Exceptional Conditions
Mattermost Confluence Plugin version <1.5.0 fails to handle unexpected request body which allows attackers to crash the plugin via constant hit to server webhook endpoint with an invalid request body.
- 7.5 High severity
Mattermost Confluence Plugin: Improper Check for Unusual or Exceptional Conditions
Mattermost Confluence Plugin version <1.5.0 fails to handle unexpected request body which allows attackers to crash the plugin via constant hit to update channel subscription endpoint with an invalid request body.
- 7.2 High severity
Mattermost Confluence Plugin: Missing Authentication for Critical Functionality
Mattermost Confluence Plugin version <1.5.0 fails to check the authorization of the user to the Mattermost instance which allows attackers to create a channel subscription without proper authorization via API call to the create channel subscription endpoint.
- 9.9 Critical severity
Mattermost: Uncontrolled Search Path Element
Mattermost versions 10.5.x <= 10.5.5, 9.11.x <= 9.11.15, 10.8.x <= 10.8.0, 10.7.x <= 10.7.2, 10.6.x <= 10.6.5 fail to sanitize filenames in the archive extractor which allows authenticated users to write files to arbitrary locations on the filesystem via uploa
- 7.5 High severity
Mattermost: Improper Validation of Specified Type of Input
Mattermost versions 10.4.x <= 10.4.2, 10.5.x <= 10.5.0, 9.11.x <= 9.11.10 fail to properly validate the props used by the RetrospectivePost custom post type in the Playbooks plugin, which allows an attacker to create a specially crafted post with maliciously c
- 7.5 High severity
Mattermost: Allocation of Resources Without Limits or Throttling
Mattermost versions 10.4.x <= 10.4.2, 10.5.x <= 10.5.0, 9.11.x <= 9.11.10 fail to validate the uniqueness and quantity of task actions within the UpdateRunTaskActions GraphQL operation, which allows an attacker to create task items containing an excessive numb
- 7.5 High severity
Mattermost Mobile Apps versions <=2.25.0 fail to terminate sessions during logout under…
Mattermost Mobile Apps versions <=2.25.0 fail to terminate sessions during logout under certain conditions (e.g. poor connectivity), allowing unauthorized users on shared devices to access sensitive notification content via continued mobile notifications
- 8.8 High severity
Mattermost: Improper Neutralization of Special Elements used in a Command
Mattermost versions 10.4.x <= 10.4.2, 10.3.x <= 10.3.3, 9.11.x <= 9.11.8 fail to restrict command execution in archived channels, which allows authenticated users to run commands in archived channels.
- 8.8 High severity
Mattermost: Missing Authentication for Critical Functionality
Mattermost versions 10.4.x <= 10.4.2, 10.3.x <= 10.3.3, 9.11.x <= 9.11.8, 10.5.x <= 10.5.0 fail to enforce MFA on plugin endpoints, which allows authenticated attackers to bypass MFA protections via API requests to plugin-specific routes.
- 7.5 High severity
Mattermost: Improper Limitation of a Pathname to a Restricted Directory
Mattermost versions 10.4.x <= 10.4.1, 9.11.x <= 9.11.7, 10.3.x <= 10.3.2, 10.2.x <= 10.2.2 fail to properly validate board blocks when importing boards which allows an attacker could read any arbitrary file on the system via importing and exporting a specially
- 8.8 High severity
Mattermost: Session Fixation
Mattermost versions 9.11.x <= 9.11.6, 10.4.x <= 10.4.1 fail to invalidate all active sessions when converting a user to a bot, with allows the converted user to escalate their privileges depending on the permissions granted to the bot.