WordPress Fancy Product Designer for WooCommerce plugin versions prior to 4.5.1 suffer from a persistent cross site scripting vulnerability.
## About Fancy Product Designer for WooCommerce
Fancy Product Designer for WooCommerce is a WordPress plugin which allows users to design custom products in a vendor's WooCommerce store. It is sold through the third-party marketplace "Envato Market" and boasts over 15,000 sales.
## Stored XSS via SVG upload
The "Require Login" setting in FPD before version 4.5.1 does not succeed in requiring users to be logged in to upload files, meaning any unauthenticated user can exploit this vulnerability.
This vulnerability can result in the takeover of any user's account on the affected domain. If an SVG containing a stored XSS payload is opened by a logged in administrator, it could lead to the compromise of the entire site. If opened by an anonymous user, it could attempt to phish the user's credentials by imitating a WordPress login page.
SVGs accessed in this way can trivially read out current `_wpnonce` values, giving an attacker unfettered access to the entire WordPress API of an affected site.
### Proof of Concept
- Account takeover SVG: [change-user-email.svg](https://github.com/jdgregson/Disclosures/blob/master/fancy-product-designer/stored-xss-via-svg-upload/change-user-email.svg)
- Demo video: [stored-xss-account-takover.mp4](https://raw.githubusercontent.com/jdgregson/Disclosures/master/fancy-product-designer/stored-xss-via-svg-upload/stored-xss-account-takover.mp4)
### Disclosure Timeline
- 10/10/2020: issue reported via ticket on developer's support form
- 10/11/2020: developer responded discussing potential mitigations
- 10/20/2020: developer released an update which did not address the issue
- 10/26/2020: developer released an update which addressed the issue by only allowing a subset of tags and attributes in uploaded SVGs
- 11/15/2020: full disclosure