CVE-2025-8399 Mmm Unity Loader <= 1.0 - Authenticated (Contributor+) Stored Cross-Site Scripting via attributes Parameter
Authenticated attackers with Contributor access can inject arbitrary scripts via the attributes parameter, leading to script execution on victim pages.
- 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-2025-8399?
CVE-2025-8399 is a medium-severity cross-site scripting vulnerability in mmanifesto Mmm Unity Loader, published on 2 Aug 2025. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
The Mmm Unity Loader plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the ‘attributes’ parameter in all versions up to, and including, 1.0 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with Contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
Weakness: CWE-79
Which versions are affected by CVE-2025-8399?
How do I fix CVE-2025-8399?
No fix has been published for CVE-2025-8399 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2025-8399 being exploited?
There is no known exploitation of CVE-2025-8399 in the wild and no public exploit code.
Sources
Also known as GHSA-3cq9-x9vj-w2qm.