A malicious X-ProxyContextPath or X-Forwarded-Context header containing external resources or embedded code could cause remote code execution. The fix to properly handle these headers was applied on the Apache NiFi 1.5.0 release. Users running a prior 1.x release should upgrade to the appropriate release.
An authorized user could upload a template which contained malicious code and accessed sensitive files via an XML External Entity (XXE) attack. The fix to properly handle XML External Entities was applied on the Apache NiFi 1.4.0 release. Users running a prior 1.x release should upgrade to the appropriate release.
In Apache NiFi before 0.7.4 and 1.x before 1.3.0, there are certain user input components in the UI which had been guarding for some forms of XSS issues but were insufficient.