CVE-2025-6227 Invite token is used as part of the secure communication

What is CVE-2025-6227?

CVE-2025-6227 is a low-severity vulnerability in Mattermost Mattermost Server, published on 18 Jul 2025. An attacker needs administrator access to exploit it, with no action from the victim.

Official description

Mattermost versions 10.5.x <= 10.5.7, 9.11.x <= 9.11.16 fail to negotiate a new token when accepting the invite which allows a user that intercepts both invite and password to send synchronization payloads to the server that originally created the invite via the REST API.

Weakness: CWE-522

Which versions are affected by CVE-2025-6227?

10 open source packages ship an affected version, including github.com/mattermost/mattermost-server, github.com/mattermost/mattermost-server/v5 and github.com/mattermost/mattermost-server/v6. It affects 1 product.

Products include Mattermost Mattermost Server.

How do I fix CVE-2025-6227?

Upgrade github.com/mattermost/mattermost-server to a fixed version for your release line: 10.5.8, 9.11.17, 9.11.17+incompatible or 10.5.8+incompatible.

Is CVE-2025-6227 being exploited?

There is no known exploitation of CVE-2025-6227 in the wild and no public exploit code.

Other vulnerabilities in Mattermost Mattermost Server

• CVE-2025-12419 Account takeover on OAuth/OpenID-enabled servers Critical 9.9
• CVE-2025-12421 Account Takeover via Code Exchange Endpoint Critical 9.9
• CVE-2025-4981 Path Traversal Leading to RCE by Any Authenticated Mattermost User Critical 9.9
• CVE-2025-20051 Arbitrary file read via block duplication in Mattermost Boards Critical 9.9
• CVE-2025-25279 Arbitrary file read in Mattermost Boards via import & export board archive Critical 9.9

All Mattermost Mattermost Server vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-4fwj-8595-wp25, GO-2025-3818.