What is CVE-2026-16046?

CVE-2026-16046 is a medium-severity vulnerability in Mattermost, classified under Incorrect Authorization. CVSS score: 4.3/10. Published 2026-08-17.

How severe is CVE-2026-16046?

Medium severity. CVSS v3 base score is 4.3 out of 10.

Auth bypass in Mattermost

CVE-2026-16046

Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21 fail to enforce run-state validation on write operations for finished playbook runs which allows a run participant to modify status, checklists, retrospective content, ownership, and participants on completed runs via REST and GraphQL API requests. Mattermost Advisory ID: MMSA-2026-00675

Vulnerability class: Broken Access Control

CVSS v3 metric

CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N.

Affected products

Mattermost — versions 11.7.0, 10.11.0, 11.9.0

Weakness classification (CWE)

CWE-863 — Incorrect Authorization

References

responsibledisclosure@mattermost.com (vendor-advisory)

Frequently asked questions

What is CVE-2026-16046?: CVE-2026-16046 is a medium-severity vulnerability in Mattermost, classified under Incorrect Authorization. CVSS score: 4.3/10. Published 2026-08-17.
How severe is CVE-2026-16046?: Medium severity. CVSS v3 base score is 4.3 out of 10.