CVE-2026-6334

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

CVSS v3.1 Score

3.1

LOW

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

EPSS — Exploit Prediction

0.0003

Probability of exploitation

0.07%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-305 CWE-305

References

Other References

https://mattermost.com/security-updates

Frequently Asked Questions

What is CVE-2026-6334? +

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 It has a CVSS v3.1 base score of 3.1 (LOW).

How severe is CVE-2026-6334? +

CVE-2026-6334 has a CVSS v3.1 score of 3.1 out of 10, rated LOW. This is a low-severity vulnerability with limited impact. The EPSS score is 0.0003, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-6334? +

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.

Related Vulnerabilities

CVE-2026-40582

ChurchCRM is an open-source church management system. In versions prior to 7.2.0, the /api/public/user/login endpoint validates only the username and …

CVE-2025-53534

RatPanel is a server operation and maintenance management panel. In versions 2.3.19 through 2.5.5, when an attacker obtains the backend …

CVE-2024-1403 10.0

In OpenEdge Authentication Gateway and AdminServer prior to 11.7.19, 12.2.14, 12.8.1 on all platforms supported by the OpenEdge product, an …

CVE-2025-24522 10.0

KUNBUS Revolution Pi OS Bookworm 01/2025 is vulnerable because authentication is not configured by default for the Node-RED server. This …

CVE-2024-36388 10.0

MileSight DeviceHub - CWE-305 Missing Authentication for Critical Function

CVE-2026-4670 9.8

Authentication bypass by primary weakness vulnerability in Progress Software MOVEit Automation allows Authentication Bypass. This issue affects MOVEit Automation: from …