CVE-2025-53971: mattermost server Auth Bypass — Fix

Description

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.

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CVSS v3.1 Score

3.8

LOW

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N

Weakness Type (CWE)

CWE-863 Incorrect Authorization

Affected Products

Vendor	Product	Versions
mattermost	mattermost_server	9.11.0 — 9.11.18
mattermost	mattermost_server	10.5.0 — 10.5.9

References

Advisories & Patches

https://mattermost.com/security-updates

Frequently Asked Questions

What is CVE-2025-53971? +

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. It has a CVSS v3.1 base score of 3.8 (LOW).

How severe is CVE-2025-53971? +

CVE-2025-53971 has a CVSS v3.1 score of 3.8 out of 10, rated LOW. This is a low-severity vulnerability with limited impact.

What products are affected by CVE-2025-53971? +

CVE-2025-53971 affects products from mattermost, specifically: mattermost_server. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-53971? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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