The Apache XmlSchema walker (xmlschema-walker) doesn't detect cycles in type derivation,...

The Apache XmlSchema walker (xmlschema-walker) doesn't detect cycles in type derivation, substitution groups, model groups or attribute groups. A malicious schema with such a cycle can make the walker recurse until the stack overflows, causing a denial of service.

Users are recommended to upgrade to version 2.3.3, which fixes this issue.