When a client request to a cluster node was replicated to other nodes in the cluster for verification, the Content-Length was forwarded. On a DELETE request, the body was ignored, but if the initial request had a Content-Length value other than 0, the receiving nodes would wait for the body and eventually timeout. Mitigation: The fix to check DELETE requests and overwrite non-zero Content-Length header values was applied on the Apache NiFi 1.8.0 release. Users running a prior 1.x release should upgrade to the appropriate release.

The message-page.jsp error page used the value of the HTTP request header X-ProxyContextPath without sanitization, resulting in a reflected XSS attack. Mitigation: The fix to correctly parse and sanitize the request attribute value was applied on the Apache NiFi 1.8.0 release. Users running a prior 1.x release should upgrade to the appropriate release.

The template upload API endpoint accepted requests from different domain when sent in conjunction with ARP spoofing + man in the middle (MiTM) attack, resulting in a CSRF attack. The required attack vector is complex, requiring a scenario with client certificate authentication, same subnet access, and injecting malicious code into an unprotected (plaintext HTTP) website which the targeted user later visits, but the possible damage warranted a Severe severity level. Mitigation: The fix to apply Cross-Origin Resource Sharing (CORS) policy request filtering was applied on the Apache NiFi 1.8.0 release. Users running a prior 1.x release should upgrade to the appropriate release.