The Link Library WordPress plugin before 7.10.0 does not re-check the selected library's own login requirement when processing its front-end link submission, allowing unauthenticated users to submit links to a library configured to require login by reusing a form token obtained from another library that does not.
https://wpscan.com/vulnerability/e2cf7d5f-b9c9-4320-9fc8-4ac8c6d24f78/