WonderCMS 3.5.0 is vulnerable to Server-Side Request Forgery (SSRF) in the custom module installation functionality. An authenticated administrator can supply a malicious URL via the pluginThemeUrl POST parameter. The server fetches the provided URL using curl_exec() without sufficient validation, allowing the attacker to force internal or external HTTP requests.
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.