CVE-2026-45797 HeyForm Vulnerable to Stored XSS via Unauthenticated SVG File Upload
An attacker can upload malicious SVG files to trigger stored XSS on the HeyForm domain without authentication, potentially compromising user sessions.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-45797?
CVE-2026-45797 is a medium-severity cross-site scripting vulnerability in heyform, published on 20 Jul 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
HeyForm is an open-source form builder. Prior to version 3.0.0-rc.7, the `/api/upload` endpoint allows unauthenticated file uploads including SVG files. Uploaded SVGs are stored in the static assets directory and served with `Content-Type: image/svg+xml` by Express's serve-static middleware, allowing an attacker to achieve stored cross-site scripting (XSS) on the heyform domain without any authentication. Version 3.0.0-rc.7 contains a patch for the issue.
Which versions are affected by CVE-2026-45797?
How do I fix CVE-2026-45797?
No fix has been published for CVE-2026-45797 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-2026-45797 being exploited?
There is no known exploitation of CVE-2026-45797 in the wild and no public exploit code.
Sources
Also known as GHSA-m94h-jxvc-hhch.