What is CVE-2026-8823?

CVE-2026-8823 is a low-severity vulnerability in Mattermost, classified under Incorrect Authorization. CVSS score: 3.8/10. Published 2026-06-22.

How severe is CVE-2026-8823?

Low severity. CVSS v3 base score is 3.8 out of 10.

Auth bypass in Mattermost

CVE-2026-8823

Mattermost versions 11.7.x <= 11.7.0, 10.11.x <= 10.11.17 fail to validate bot targets when demoting users to guests which allows a lower-privileged administrator to degrade arbitrary bot accounts via the standard demote-user API.. Matterm…

Vulnerability class: Broken Access Control

CVSS v3 metric

CVSS v3 base score 3.8 (Low). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:L.

Affected products

Mattermost — versions 11.7.0, 10.11.0, 11.8.0

Weakness classification (CWE)

CWE-863 — Incorrect Authorization

References

responsibledisclosure@mattermost.com (vendor-advisory)

Frequently asked questions

What is CVE-2026-8823?: CVE-2026-8823 is a low-severity vulnerability in Mattermost, classified under Incorrect Authorization. CVSS score: 3.8/10. Published 2026-06-22.
How severe is CVE-2026-8823?: Low severity. CVSS v3 base score is 3.8 out of 10.