Github.Com Mattermost Mattermost-Server V6 vulnerabilities

CVE-2025-11776 [MEDIUM] CWE-863 Mattermost fails to properly restrict access to archived channel search API Mattermost fails to properly restrict access to archived channel search API Mattermost versions < 11 fail to properly restrict access to archived channel search API which allows guest users to discover archived public channels via the `/api/v4/teams/{team_id}/channels/search_archived` endpoint

CVE-2025-11777 [LOW] CWE-863 Mattermost Incorrect Authorization vulnerability Mattermost Incorrect Authorization vulnerability Mattermost versions 10.11.x <= 10.11.3, 10.5.x <= 10.5.11 fail to properly validate team membership permissions in the Add Channel Member API, which allows users from one team to access user metadata and channel membership information from other teams via the API endpoint.

CVE-2025-49222 [MEDIUM] CWE-434 Mattermost Fails to Validate Remote Cluster Upload Sessions Mattermost Fails to Validate Remote Cluster Upload Sessions Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.9.x <= 10.9.2, 10.10.x <= 10.10.0 fail to validate upload types in remote cluster upload sessions which allows a system admin to upload non-attachment file types via shared channels that could potentially be placed in arbitrary filesystem directories.

CVE-2025-36530 [MEDIUM] CWE-22 Mattermost Fails to Validate File Paths Mattermost Fails to Validate File Paths Mattermost versions 10.9.x <= 10.9.1, 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17 fail to properly validate file paths during plugin import operations which allows restricted admin users to install unauthorized custom plugins via path traversal in the import functionality, bypassing plugin signature enforcement and marketplace restrictions.

CVE-2025-8402 [MEDIUM] CWE-476 Mattermost has Potential Server Crash due to Unvalidated Import Data Mattermost has Potential Server Crash due to Unvalidated Import Data Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.10.x <= 10.10.0, 10.9.x <= 10.9.3 fail to validate import data which allows a system admin to crash the server via the bulk import feature.

CVE-2025-8023 [MEDIUM] CWE-22 Mattermost Fails to Sanitize Path Traversal Sequences Mattermost Fails to Sanitize Path Traversal Sequences Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.9.x <= 10.9.2 fails to sanitize path traversal sequences in template file destination paths, which allows a system admin to perform path traversal attacks via malicious path components, potentially enabling malicious file placement outside intended directories.

CVE-2025-47870 [MEDIUM] CWE-306 Mattermost Does Not Sanitize the Team Invite ID Mattermost Does Not Sanitize the Team Invite ID Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.9.x <= 10.9.2 fail to sanitize the team invite ID in the POST /api/v4/teams/:teamId/restore endpoint which allows an team admin with no member invite privileges to get the team’s invite id.

CVE-2025-53971 [LOW] CWE-863 Mattermost Fails to Properly Validate Team Role Modification Mattermost Fails to Properly Validate Team Role Modification Mattermost versions 10.5.x <= 10.5.8, 9.11.x <= 9.11.17 fail to properly validate authorization for team scheme role modifications which allows Team Admins to demote Team Members to Guests via the PUT /api/v4/teams/team-id/members/user-id/schemeRoles API endpoint.

CVE-2024-39837 [LOW] CWE-284 Mattermost did not properly restrict channel creation Mattermost did not properly restrict channel creation Mattermost versions 9.9.x <= 9.9.0, 9.5.x <= 9.5.6 fail to properly restrict channel creation which allows a malicious remote to create arbitrary channels, when shared channels were enabled.

CVE-2024-28053 [LOW] CWE-400 Mattermost Server Resource Exhaustion Mattermost Server Resource Exhaustion Resource Exhaustion in Mattermost Server versions 8.1.x before 8.1.10 fails to limit the size of the payload that can be read and parsed allowing an attacker to send a very large email payload and crash the server.

CVE-2023-47858 [MEDIUM] CWE-284 Mattermost viewing archived public channels permissions vulnerability Mattermost viewing archived public channels permissions vulnerability 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//channels/deleted endpoint.

CVE-2023-48732 [MEDIUM] CWE-200 Mattermost notified all users in the channel when using WebSockets to respond individually Mattermost notified all users in the channel when using WebSockets to respond individually 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.

CVE-2023-6458 [HIGH] CWE-22 Mattermost Injection vulnerability Mattermost Injection vulnerability Mattermost webapp fails to validate route parameters in//channels/ allowing an attacker to perform a client-side path traversal.

CVE-2023-6459 [MEDIUM] CWE-200 Mattermost Exposure of Sensitive Information to an Unauthorized Actor vulnerability Mattermost Exposure of Sensitive Information to an Unauthorized Actor vulnerability Mattermost is grouping calls in the /metrics endpoint by id and reports that id in the response. Since this id is the channelID, the public /metrics endpoint is revealing channelIDs.

CVE-2023-48369 [MEDIUM] CWE-400 Mattermost Uncontrolled Resource Consumption vulnerability Mattermost Uncontrolled Resource Consumption vulnerability Mattermost fails to limit the log size of server logs allowing an attacker sending specially crafted requests to different endpoints to potentially overflow the log.

CVE-2023-45223 [MEDIUM] CWE-200 Mattermost Exposure of Sensitive Information to an Unauthorized Actor vulnerability Mattermost Exposure of Sensitive Information to an Unauthorized Actor vulnerability Mattermost fails to properly validate the "Show Full Name" option in a few endpoints in Mattermost Boards, allowing a member to get the full name of another user even if the Show Full Name option was disabled.

CVE-2023-6202 [MEDIUM] CWE-284 Mattermost Improper Access Control vulnerability Mattermost Improper Access Control vulnerability Mattermost fails to perform proper authorization in the `/plugins/focalboard/api/v2/users` endpoint allowing an attacker who is a guest user and knows the ID of another user to get their information (e.g. name, surname, nickname) via Mattermost Boards.

CVE-2023-47168 [MEDIUM] CWE-601 Mattermost Open Redirect vulnerability Mattermost Open Redirect vulnerability Mattermost fails to properly check a redirect URL parameter allowing for an open redirect was possible when the user clicked "Back to Mattermost" after providing a invalid custom url scheme in /oauth/{service}/mobile_login?redirect_to=

CVE-2023-40703 [MEDIUM] CWE-400 Mattermost Uncontrolled Resource Consumption vulnerability Mattermost Uncontrolled Resource Consumption vulnerability Mattermost fails to properly limit the characters allowed in different fields of a block in Mattermost Boards allowing a attacker to consume excessive resources, possibly leading to Denial of Service, by patching the field of a block using a specially crafted string.

CVE-2023-47865 [MEDIUM] CWE-284 Mattermost Improper Access Control vulnerability Mattermost Improper Access Control vulnerability Mattermost fails to check if hardened mode is enabled when overriding the username and/or the icon when posting a post. If settings allowed integrations to override the username and profile picture when posting, a member could also override the username and icon when making a post even if the Hardened Mode setting was enabled