CVE-2025-66500 Foxit webplugins.foxit.com Stored Cross-Site Scripting via postMessage Vulnerability

Medium 6.3 Published 19 Dec 2025 Updated 19 Dec 2025

An attacker can execute arbitrary JavaScript in Foxit web plugins via a stored XSS vulnerability in the postMessage handler.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Over the internet
Victim action needed: A user has to click or open something
Fix: None listed

What is CVE-2025-66500?

CVE-2025-66500 is a medium-severity cross-site scripting vulnerability in webplugins.foxit.com, published on 19 Dec 2025. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

Official description

A stored cross-site scripting (XSS) vulnerability exists in webplugins.foxit.com. A postMessage handler fails to validate the message origin and directly assigns externalPath to a script source, allowing an attacker to execute arbitrary JavaScript when a crafted postMessage is received.

Weakness: CWE-79

Which versions are affected by CVE-2025-66500?

It affects 1 product.

Products include Foxit Pdf Editor Cloud.

How do I fix CVE-2025-66500?

No fix has been published for CVE-2025-66500 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-2025-66500 being exploited?

There is no known exploitation of CVE-2025-66500 in the wild and no public exploit code.

Sources

Also known as GHSA-w247-2vxj-mgr3.