CVE-2025-56236 FormCms avatar upload feature has a stored cross-site scripting (XSS) vulnerability
Authenticated users can upload malicious HTML files via avatar feature, leading to stored XSS and potential account takeover when privileged users access them.
- 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
- Available
What is CVE-2025-56236?
CVE-2025-56236 is a medium-severity cross-site scripting vulnerability in n/a, published on 28 Aug 2025. 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
FormCms v0.5.5 contains a stored cross-site scripting (XSS) vulnerability in the avatar upload feature. Authenticated users can upload .html files containing malicious JavaScript, which are accessible via a public URL. When a privileged user accesses the file, the script executes in their browser context.
Weakness: CWE-79
Which versions are affected by CVE-2025-56236?
2 open source packages ship an affected version, including FormCMS. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
FormCMS NuGet | All versions | 0.5.7 |
FormCMS NuGet | All versions | 0.5.7 |
Products include Formcms Formcms.
How do I fix CVE-2025-56236?
Upgrade FormCMS to 0.5.7 or later.
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-2025-56236 being exploited?
There is no known exploitation of CVE-2025-56236 in the wild and no public exploit code.
Other vulnerabilities in n/a
Sources
Also known as GHSA-4fxf-xgrm-8fcj.