CVE-2026-3524 Authorization Bypass in Mattermost Legal Hold Plugin Due to Missing Return After Permission Check
An authenticated attacker can bypass authorization checks to access, create, download, and delete legal hold data in the Mattermost Legal Hold Plugin.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-3524?
CVE-2026-3524 is a high-severity missing authorization vulnerability in Mattermost, published on 6 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
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
Weakness: CWE-862
Which versions are affected by CVE-2026-3524?
It affects 1 product.
Products include Mattermost Legal Hold.
How do I fix CVE-2026-3524?
No fix has been published for CVE-2026-3524 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-3524 being exploited?
There is no known exploitation of CVE-2026-3524 in the wild and no public exploit code.
Other vulnerabilities in Mattermost
Sources
Also known as GHSA-h7g6-pq3g-f7cw.