Apache NiFi before 0.7.4 and 1.x before 1.3.0 need to establish the response header telling browsers to only allow framing with the same origin.
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 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.
When using an authentication mechanism other than PKI, when the user clicks Log Out in NiFi versions 1.0.0 to 1.9.2, NiFi invalidates the authentication token on the client side but not on the server side. This permits the user's client-side token to be used for up to 12 hours after logging out to make API requests to NiFi.
In Apache NiFi 1.10.0 to 1.11.4, the NiFi stateless execution engine produced log output which included sensitive property values. When a flow was triggered, the flow definition configuration JSON was printed, potentially containing sensitive values in plaintext.
In Apache NiFi 1.0.0 to 1.11.4, the NiFi download token (one-time password) mechanism used a fixed cache size and did not authenticate a request to create a download token, only when attempting to use the token to access the content. An unauthenticated user could repeatedly request download tokens, preventing legitimate users from requesting download tokens.
In Apache NiFi 1.2.0 to 1.11.4, the NiFi UI and API were protected by mandating TLS v1.2, as well as listening connections established by processors like ListenHTTP, HandleHttpRequest, etc. However intracluster communication such as cluster request replication, Site-to-Site, and load balanced queues continued to support TLS v1.0 or v1.1.