CVE-2026-9571
Published:July 13, 2026
Updated:July 21, 2026
Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to invalidate OAuth refresh tokens upon user account deactivation, which allows a deactivated user or an attacker in possession of a valid refresh token to obtain new functional access tokens via the OAuth refresh token grant endpoint.. Mattermost Advisory ID: MMSA-2026-00680
Affected Packages
https://github.com/mattermost/mattermost.git (GITHUB):
Affected version(s) >=v11.6.0 <v11.6.5Fix Suggestion:
Update to version v11.6.5https://github.com/mattermost/mattermost.git (GITHUB):
Affected version(s) >=v10.11.0 <v10.11.20Fix Suggestion:
Update to version v10.11.20https://github.com/mattermost/mattermost.git (GITHUB):
Affected version(s) >=v11.7.0 <v11.7.3Fix Suggestion:
Update to version v11.7.3github.com/mattermost/mattermost (GO):
Affected version(s) >=v11.7.0 <v11.7.3Fix Suggestion:
Update to version v11.7.3github.com/mattermost/mattermost (GO):
Affected version(s) >=v10.11.0 <v10.11.20Fix Suggestion:
Update to version v10.11.20github.com/mattermost/mattermost (GO):
Affected version(s) >=v11.6.0 <v11.6.5Fix Suggestion:
Update to version v11.6.5Related Resources (1)
Do you need more information?
Contact UsCVSS v4
Base Score:
7.4
Attack Vector
NETWORK
Attack Complexity
HIGH
Attack Requirements
NONE
Privileges Required
HIGH
User Interaction
NONE
Vulnerable System Confidentiality
HIGH
Vulnerable System Integrity
HIGH
Vulnerable System Availability
NONE
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
5.9
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
HIGH
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
NONE
Weakness Type (CWE)
Authentication Bypass by Primary Weakness
EPSS
Base Score:
0.17