CVE-2026-6739

Name: CVE-2026-6739
Creator: NVD / NIST
Published: 2026-06-12T17:16:27.29+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.2/10EPSS 0.26%

Last modified Jun 18, 2026

CVE-2026-6739 is a high-severity vulnerability rated 7.2/10 on the CVSS scale. Mattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15, 10.11.x <= 10.11.16 fail to require system-level permission when patching protected default system roles, which allows authenticated users with delegated user-management permissions to escalate privileges by altering built-in role permissions via the role patch API.. Mattermost Advisory ID: MMSA-2026-00656. EPSS estimates a 0.26% chance of exploitation in the next 30 days.

Description

Mattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15, 10.11.x <= 10.11.16 fail to require system-level permission when patching protected default system roles, which allows authenticated users with delegated user-management permissions to escalate privileges by altering built-in role permissions via the role patch API.. Mattermost Advisory ID: MMSA-2026-00656

Metrics

CVSS 3.1

7.2/10

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

EPSS Probability

0.26%

17.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-863

Affected Software

Vendor	Product	Versions
Mattermost	Mattermost Server	>= 10.11.0, < 10.11.17
Mattermost	Mattermost Server	>= 11.5.0, < 11.5.5
Mattermost	Mattermost Server	>= 11.6.0, < 11.6.2

References

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

Timeline

Published: Jun 12, 2026
Last Modified: Jun 18, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-6739?

How severe is CVE-2026-6739?

CVE-2026-6739 has a CVSS score of 7.2/10 (HIGH severity). The EPSS model estimates a 0.26% probability of exploitation in the next 30 days.

How do I fix CVE-2026-6739?

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-2026-6739?

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

Scan your code now

Source: NVD / NIST