CVE-2026-1591 Stored XSS via Attachments Feature in https://pdfonline.foxit.com/

Medium 6.3 Published 3 Feb 2026 Updated 3 Feb 2026

Attackers can execute arbitrary JavaScript in victim browsers via stored XSS in the file upload feature of Foxit PDF Editor Cloud.

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-2026-1591?

CVE-2026-1591 is a medium-severity cross-site scripting vulnerability in pdfonline.foxit.com, published on 3 Feb 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

Official description

Foxit PDF Editor Cloud (pdfonline) contains a stored cross-site scripting vulnerability in the file upload feature. A malicious username is embedded into the upload file list without proper escaping, allowing arbitrary JavaScript execution when the list is displayed.

This issue affects pdfonline.foxit.com: before 2026‑02‑03.

Weakness: CWE-79

Which versions are affected by CVE-2026-1591?

It affects 1 product.

Products include Foxit Pdf Editor Cloud.

How do I fix CVE-2026-1591?

No fix has been published for CVE-2026-1591 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-2026-1591 being exploited?

There is no known exploitation of CVE-2026-1591 in the wild and no public exploit code.

Sources

Also known as GHSA-g4wf-v389-9w53.