CVE-2026-6334

Name: CVE-2026-6334
Creator: NVD / NIST
Published: 2026-05-18T08:16:14.313+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

LOWCVSS 3.8/10EPSS 0.12%

Last modified Jun 17, 2026

CVE-2026-6334 is a low-severity vulnerability rated 3.8/10 on the CVSS scale. 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. EPSS estimates a 0.12% chance of exploitation in the next 30 days.

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

Metrics

CVSS 3.1

3.8/10

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

EPSS Probability

0.12%

2.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-305

Affected Software

Vendor	Product	Versions
Mattermost	Mattermost Server	>= 10.11.0, < 10.11.14
Mattermost	Mattermost Server	>= 11.5.0, < 11.5.2

References

https://mattermost.com/security-updatesVendor Advisory

Timeline

Published: May 18, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-6334?

How severe is CVE-2026-6334?

CVE-2026-6334 has a CVSS score of 3.8/10 (LOW severity). The EPSS model estimates a 0.12% probability of exploitation in the next 30 days.

How do I fix CVE-2026-6334?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-6334?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST