What is CVE-2026-10085?

CVE-2026-10085 is a medium-severity vulnerability in Mattermost, classified under Missing Authorization. CVSS score: 5.4/10. Published 2026-07-13.

How severe is CVE-2026-10085?

Medium severity. CVSS v3 base score is 5.4 out of 10.

Auth bypass in Mattermost

CVE-2026-10085

Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to restrict the group_constrained channel flag to public and private channels that support group synchronization, which allows an ordinary group or direct message member to remove all participants from the conversation via the channel patch API.. Mattermost Advisory ID: MMSA-2026-00688

Vulnerability class: Broken Access Control

EPSS: 0.003 (20.7th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L.

Affected products

Mattermost — versions 11.7.0, 11.6.0, 10.11.0
Mattermost Mattermost_server

Weakness classification (CWE)

CWE-862 — Missing Authorization

References

responsibledisclosure@mattermost.com (vendor-advisory, Vendor Advisory)

Frequently asked questions

What is CVE-2026-10085?: CVE-2026-10085 is a medium-severity vulnerability in Mattermost, classified under Missing Authorization. CVSS score: 5.4/10. Published 2026-07-13.
How severe is CVE-2026-10085?: Medium severity. CVSS v3 base score is 5.4 out of 10.