CVE-2025-9081 IDOR in board file download allows any user to download any file by UUID

What is CVE-2025-9081?

CVE-2025-9081 is a low-severity missing authorization vulnerability in Mattermost Mattermost Server, published on 19 Sep 2025. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

Mattermost versions 10.5.x <= 10.5.8, 9.11.x <= 9.11.17 fail to properly validate access controls which allows any authenticated user to download sensitive files via board file download endpoint using UUID enumeration

Weakness: CWE-639

Which versions are affected by CVE-2025-9081?

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

Products include Mattermost Mattermost Server.

How do I fix CVE-2025-9081?

Upgrade github.com/mattermost/mattermost-server to a fixed version for your release line: 10.5.9, 9.11.18, 9.11.18+incompatible or 10.5.9+incompatible.

Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.

Is CVE-2025-9081 being exploited?

There is no known exploitation of CVE-2025-9081 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-f72g-52v7-mg3p, GO-2025-3978.