What is CVE-2026-3524?

CVE-2026-3524 is a high-severity vulnerability in Mattermost Legal Hold, classified under Missing Authorization. CVSS score: 8.8/10. Published 2026-04-06.

How severe is CVE-2026-3524?

High severity. CVSS v3 base score is 8.8 out of 10.

Auth bypass in Mattermost Legal Hold

CVE-2026-3524

Mattermost Plugin Legal Hold versions <=1.1.4 fail to halt request processing after a failed authorization check in ServeHTTP which allows an authenticated attacker to access, create, download, and delete legal hold data via crafted API requests to the plugin's endpoints. Mattermost Advisory ID: MMSA-2026-00621

Vulnerability class: Broken Access Control

EPSS: 0.004 (30.5th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

Affected products

Mattermost Legal_hold
Mattermost — versions 0, 1.1.5

Weakness classification (CWE)

CWE-862 — Missing Authorization

References

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

Frequently asked questions

What is CVE-2026-3524?: CVE-2026-3524 is a high-severity vulnerability in Mattermost Legal Hold, classified under Missing Authorization. CVSS score: 8.8/10. Published 2026-04-06.
How severe is CVE-2026-3524?: High severity. CVSS v3 base score is 8.8 out of 10.