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Mattermost Fails to Properly Validate Team Role Modification

Low severity GitHub Reviewed Published Aug 21, 2025 to the GitHub Advisory Database • Updated Aug 29, 2025

Package

gomod github.com/mattermost/mattermost-server (Go)

Affected versions

>= 10.5.0, <= 10.5.8
>= 9.11.0, <= 9.11.17

Patched versions

10.5.9
9.11.18
gomod github.com/mattermost/mattermost-server/v5 (Go)
<= 5.39.3
None
gomod github.com/mattermost/mattermost-server/v6 (Go)
<= 6.7.2
None
gomod github.com/mattermost/mattermost/server/v8 (Go)
< 8.0.0-20250721095846-c602a4a78e1f
8.0.0-20250721095846-c602a4a78e1f

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.

References

Published by the National Vulnerability Database Aug 21, 2025
Published to the GitHub Advisory Database Aug 21, 2025
Reviewed Aug 21, 2025
Last updated Aug 29, 2025

Severity

Low

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
High
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(10th percentile)

Weaknesses

Incorrect Authorization

The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. This allows attackers to bypass intended access restrictions. Learn more on MITRE.

CVE ID

CVE-2025-53971

GHSA ID

GHSA-4276-cm8c-788h

Source code

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