CVE-2025-55070 Lack of MFA enforcement in WebSocket connections

What is CVE-2025-55070?

CVE-2025-55070 is a medium-severity authentication bypass vulnerability in Mattermost Mattermost Server, published on 14 Nov 2025. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

Mattermost versions <11 fail to enforce multi-factor authentication on WebSocket connections which allows unauthenticated users to access sensitive information via WebSocket events

Weakness: CWE-306

Which versions are affected by CVE-2025-55070?

8 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-2025-55070?

Upgrade github.com/mattermost/mattermost-server to a fixed version for your release line: 11.1.0 or 11.1.0+incompatible.

Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.

Is CVE-2025-55070 being exploited?

There is no known exploitation of CVE-2025-55070 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-xpg8-8xpv-948p, GO-2025-4128, MINI-cjc2-f5r8-2r9m, MINI-vffv-r52g-79jq.