Idno is a social publishing platform. Prior to version 1.6.4, a logic error in the API authentication flow causes the CSRF protection on the URL unfurl service endpoint to be trivially bypassed by any unauthenticated remote attacker. Combined with the absence of a login requirement on the endpoint itself, this allows an attacker to force the server to make arbitrary outbound HTTP requests to any host, including internal network addresses and cloud instance metadata services, and retrieve the response content. This issue has been patched in version 1.6.4.