Ghost is a Node.js content management system. From 6.26.0 until 6.54.1, a validation issue allowed some functionality, such as Webmentions, to be abused by an unauthenticated user to make limited HTTP requests to hosts in the Ghost servers internal network. A successful attack would not result in any response data being returned. This vulnerability is fixed in 6.54.1.
Weakness
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.