Mattermost

One of the API in Mattermost version 6.4.1 and earlier fails to properly protect the permissions, which allows the authenticated members with restricted custom admin role to bypass the restrictions and view the server logs and server config.json file contents.

A stack overflow bug in the document extractor in Mattermost Server in versions up to and including 6.3.2 allows an attacker to crash the server via submitting a maliciously crafted Apple Pages document.

Mattermost 6.3.0 and earlier fails to protect email addresses of the creator of the team via one of the APIs, which allows authenticated team members to access this information resulting in sensitive & private information disclosure.

Mattermost Boards plugin v0.10.0 and earlier fails to protect email addresses of all users via one of the Boards APIs, which allows authenticated and unauthorized users to access this information resulting in sensitive & private information disclosure.

Mattermost 6.2 and earlier fails to sufficiently process a specifically crafted GIF file when it is uploaded while drafting a post, which allows authenticated users to cause resource exhaustion while processing the file, resulting in server-side Denial of Service.

An issue was discovered in Mattermost Server before 3.8.2, 3.7.5, and 3.6.7. API endpoint access control does not honor an integration permission restriction.

An issue was discovered in Mattermost Server before 4.0.0, 3.10.2, and 3.9.2, when used as an OAuth 2.0 service provider, Session invalidation was mishandled.

An issue was discovered in Mattermost Server before 3.0.0. It does not ensure that a cookie is used over SSL.

An issue was discovered in Mattermost Server before 3.0.0. It allows attackers to obtain sensitive information about team URLs via an API.

An issue was discovered in Mattermost Server before 3.1.0. It allows XSS via theme color-code values.

An issue was discovered in Mattermost Server before 3.2.0. Attackers could read LDAP fields via injection.

An issue was discovered in Mattermost Server before 3.2.0. It allowed crafted posts that could cause a web browser to hang.

An issue was discovered in Mattermost Server before 3.5.1. E-mail address verification can be bypassed.

An issue was discovered in Mattermost Server before 3.8.2, 3.7.5, and 3.6.7. E-mail notifications can have spoofed links.

An issue was discovered in Mattermost Server before 4.1.0, 4.0.4, and 3.10.3. It allows attackers to discover a team invite ID by requesting a JSON document.

An issue was discovered in Mattermost Server before 4.2.0, 4.1.1, and 4.0.5. It allows crafted posts that potentially cause a web browser to hang.

An issue was discovered in Mattermost Server before 4.2.0, 4.1.1, and 4.0.5. It allows attackers to add DEBUG lines to the logs via a REST API version 3 logging endpoint.

An issue was discovered in Mattermost Server before 4.2.0, 4.1.1, and 4.0.5. It allows attackers to obtain sensitive information (user statuses) via a REST API version 4 endpoint.

An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2. It allows an attacker to create a button that, when pressed by a user, launches an API request.

An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2. An attacker could create fictive system-message posts via webhooks and slash commands, in the v3 or v4 REST API.

An issue was discovered in Mattermost Server before 5.1. It allows attackers to bypass intended access restrictions (for group-message channel creation) via the Group message slash command.

An issue was discovered in Mattermost Server before 5.2, 5.1.1, 5.0.3, and 4.10.3. Attackers could use multiple e-mail addresses to bypass a domain-based policy for signups.

An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2. It allows attackers to cause a denial of service (channel invisibility) via a misformatted post.

An issue was discovered in Mattermost Server before 5.7, 5.6.3, 5.5.2, and 4.10.5. It mishandles permissions for user-access token creation.

An issue was discovered in Mattermost Server before 5.8.0, when Town Square is set to Read-Only. Users can pin or unpin a post.

An issue was discovered in Mattermost Server before 5.8.0, 5.7.2, 5.6.5, and 4.10.7. Changes to e-mail addresses do not require credential re-entry.

An issue was discovered in Mattermost Server before 5.9.0, 5.8.1, 5.7.3, and 4.10.8. Changes, within the application, to e-mail addresses are mishandled.

An issue was discovered in Mattermost Server before 4.8.1, 4.7.4, and 4.6.3. An e-mail invite accidentally included the team invite_id, which leads to unintended excessive invitation privileges.

An issue was discovered in Mattermost Server before 5.1. Non-members of a channel could use the Channel PATCH API to modify that channel.

An issue was discovered in Mattermost Server before 5.1. An attacker can bypass intended access control (for direct-message channel creation) via the Message slash command.

An issue was discovered in Mattermost Server before 5.1, 5.0.2, and 4.10.2. An attacker could use the invite_people slash command to invite a non-permitted user.

An issue was discovered in Mattermost Server before 4.5.0, 4.4.5, and 4.3.4. It mishandled webhook access control in the EnableOnlyAdminIntegrations case.

An issue was discovered in Mattermost Server before 5.10.0. An attacker can bypass the intended appearance of the Edited flag after changing a post's file ID.

An issue was discovered in Mattermost Server before 5.10.0, 5.9.1, 5.8.2, and 4.10.9. A non-member could change the Update/Patch Channel endpoint for a private channel.

An issue was discovered in Mattermost Server before 5.11.0. An attacker can interfere with a channel's post loading via one crafted post.

An issue was discovered in Mattermost Server before 5.12.0. Use of a Proxy HTTP header, rather than the source address in an IP packet header, for obtaining IP address information was mishandled.

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 null entries in Microsoft Graph webhook notification payloads, which allows an unauthenticated attacker to crash the Microsoft Calendar plugin process and deny calendar…

The Mattermost Google Drive plugin before version 1.1.0 fails to validate channel membership in the file creation endpoint, allowing authenticated users with a connected Google account to share Google Drive files to unauthorized private channels and disclose private channel…

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 validate that a username returned during bot registration belongs to a bot account, which allows an unprivileged attacker to intercept private messages sent by plugins via…

Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 Mattermost fails to limit the size of responses from integration action endpoints, which allows an authenticated attacker to cause server memory exhaustion and denial of service via a malicious…

Mattermost versions 10.7.x <= 10.7.0, 10.6.x <= 10.6.2, 10.5.x <= 10.5.3, 9.11.x <= 9.11.12 fail to properly validate permissions when changing team privacy settings, allowing team administrators without the 'invite user' permission to access and modify team invite IDs via the…

Mattermost Desktop App versions <=5.8.0 fail to specify an absolute path when searching the cmd.exe file, which allows a local attacker who is able to put an cmd.exe file in the Downloads folder of a user's machine to cause remote code execution on that machine.

Mattermost fails to properly sanitize the request to /api/v4/redirect_location allowing an attacker, sending a specially crafted request to /api/v4/redirect_location, to fill up the memory due to caching large items.

Mattermost fails to disable public Boards after the "Enable Publicly-Shared Boards" configuration option is disabled, resulting in previously-shared public Boards to remain accessible.

Mattermost fails to verify if the requestor is a sysadmin or not, before allowing `install` requests to the Apps allowing a regular user send install requests to the Apps.

When processing an email invite to a private channel on a team, Mattermost fails to validate the inviter's permission to that channel, allowing an attacker to invite themselves to a private channel.

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 action ownership which allows channel managers to update actions in other channels via the channel action update endpoint.. Mattermost Advisory ID:…

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 set permissions on downloaded bulk export which allows other local users on the server to be able to read contents of the bulk export.. Mattermost Advisory ID: MMSA-2026-00593

Mattermost Confluence Plugin version <1.5.0 fails to check the access of the user to the channel which allows attackers to create channel subscription without proper access to the channel via API call to the create channel subscription endpoint.

Mattermost Confluence Plugin version <1.5.0 fails to check the access of the user to the channel which allows attackers to create a channel subscription without proper access to the channel via API call to the edit channel subscription endpoint.