CVE-2025-66521 Foxit pdfonline.foxit.com Stored Cross-Site Scripting in Trusted Certificates Feature

Medium 6.3 Published 19 Dec 2025 Updated 19 Dec 2025

Attackers can inject malicious scripts via certificate names in Foxit PDF Online, leading to script execution when the Trusted Certificates view is loaded.

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-2025-66521?

CVE-2025-66521 is a medium-severity cross-site scripting vulnerability in pdfonline.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 pdfonline.foxit.com within the Trusted Certificates feature. A crafted payload can be injected as the certificate name, which is later rendered into the DOM without proper sanitization. As a result, the injected script executes each time the Trusted Certificates view is loaded.

Weakness: CWE-79

Which versions are affected by CVE-2025-66521?

It affects 1 product.

Products include Foxit Pdf Editor Cloud.

How do I fix CVE-2025-66521?

No fix has been published for CVE-2025-66521 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-2025-66521 being exploited?

There is no known exploitation of CVE-2025-66521 in the wild and no public exploit code.

Sources

Also known as GHSA-8wr8-qf33-p6vc.