CVE-2026-6334 Details
Description
Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13 fail to enforce client identity binding during the OAuth authorization code redemption flow which allows an authenticated OAuth client to redeem authorization codes issued to a different client via a crafted token exchange request.. Mattermost Advisory ID: MMSA-2026-00570
A vulnerability exists in Mattermost versions 11.5.x through 11.5.1 and 10.11.x through 10.11.13, where the application fails to properly enforce client identity binding during the OAuth authorization code redemption process. This flaw allows an authenticated OAuth client to misuse authorization codes intended for a different client by sending a manipulated token exchange request.
Users can upgrade to Mattermost versions 11.7.0 or 11.4.15 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 May 18, 2026References to Advisories, Solutions, and Tools
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| 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, < 10.11.14 >= 11.5.0, < 11.5.2 |
CPE
Remediation
| |
Change History
4 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| May 29, 2026 | Initial Analysis | [email protected] |
| May 18, 2026 | New CVE Received | [email protected] |