Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. In versions prior to 5.3.3 or 4.10.20, a compromised Parse Server Cloud Code Webhook target endpoint allows an attacker to use prototype pollution to bypass the Parse Server `requestKeywordDenylist` option. This issue has been patched in versions 5.3.3 and 4.10.20. There are no known workarounds.