CVE-2026-9571 Details
Description
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
A vulnerability exists in Mattermost versions 11.7.x through 11.7.2, 11.6.x through 11.6.4, and 10.11.x through 10.11.19. These versions fail to invalidate OAuth refresh tokens when a user account is deactivated. As a result, a deactivated user or an attacker with a valid refresh token can obtain new access tokens through the OAuth refresh token grant endpoint.
Users can upgrade to Mattermost versions 11.9.0, 11.8.0, 11.7.5, or 11.6.5 to address this vulnerability.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Jul 14, 2026References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.
| URL | Source(s) | Tag(s) |
|---|---|---|
| https://mattermost.com/security-updates | [email protected] | Vendor Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-305 | Authentication Bypass by Primary Weakness | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| mattermost mattermost server | >= 10.11.0, < 10.11.20 >= 11.6.0, < 11.6.5 >= 11.7.0, < 11.7.3 |
CPE
Remediation
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Change History
4 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 15, 2026 | CVE Modified | CISA-ADP |
| Jul 14, 2026 | CVE Modified | CISA-ADP |
| Jul 13, 2026 | Initial Analysis | [email protected] |
| Jul 13, 2026 | New CVE Received | [email protected] |