The optional ShellUserGroupProvider in Apache NiFi 1.10.0 to 1.16.2 and Apache NiFi Registry 0.6.0 to 1.16.2 does not neutralize arguments for group resolution commands, allowing injection of operating system commands on Linux and macOS platforms. The ShellUserGroupProvider is not included in the default configuration. Command injection requires ShellUserGroupProvider to be one of the enabled User Group Providers in the Authorizers configuration. Command injection also requires an authenticated user with elevated privileges. Apache NiFi requires an authenticated user with authorization to modify access policies in order to execute the command. Apache NiFi Registry requires an authenticated user with authorization to read user groups in order to execute the command. The resolution removes command formatting based on user-provided arguments.

If NiFi Registry 0.1.0 to 0.5.0 uses an authentication mechanism other than PKI, when the user clicks Log Out, NiFi Registry 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 Registry.