Improper Restriction of XML External Entity Reference
The JAX-RS module in Apache CXF before 3.0.12 except for 2.6.17 and 3.1.x before 3.1.9 provides a number of Atom JAX-RS MessageBodyReaders. These readers use Apache Abdera Parser which expands XML entities by default which represents a major XXE risk.
CWE-611 - Improper Restriction of XML External Entity Reference
Listed 4th in the 'OWASP Top Ten', XML External Entities (XXE) vulnerability allows attackers to provide an XML input that contains an external entity. When the XML is parsed, it can cause data extraction and manipulation, execution of commands, denial-of-service attacks, and server-side request forgery.