The WPeMatico RSS Feed Fetcher WordPress plugin before 2.8.27 does not perform a capability check before fetching a user-supplied URL and rendering the response, allowing users with contributor-level access and above to force the server to issue requests to internal-only hosts and read the responses back.
https://wpscan.com/vulnerability/9b891cf0-c663-48ae-adf4-4693b46d0529/