CVE-2022-29265: Apache NiFi: Improper Restriction of XML External Entity References in Multiple Components

[David Handermann <exceptionfactory () apache org>]

Severity: moderate

Description:

Multiple components in Apache NiFi 0.0.1 to 1.16.0 do not restrict XML External Entity references in the default 
configuration.

The Standard Content Viewer service attempts to resolve XML External Entity references when viewing formatted XML files.

The following Processors attempt to resolve XML External Entity references when configured with default property values:

- EvaluateXPath
- EvaluateXQuery
- ValidateXml

Apache NiFi flow configurations that include these Processors are vulnerable to malicious XML documents that contain 
Document Type Declarations with XML External Entity references.

The resolution disables Document Type Declarations in the default configuration for these Processors, and disallows XML 
External Entity resolution in standard services.

This issue is being tracked as NIFI-9901

Mitigation:

Disabling the Validate DTD Processor Property in EvaluateXPath and EvaluateXQuery mitigates the vulnerability for those 
Processors. No mitigation is available for the ValidateXml Processor or the Standard Content Viewer.

Credit:

David Handermann at exceptionfactory.com reported this issue.

References:

https://nifi.apache.org/security.html#CVE-2022-29265