Improper Restriction of XML External Entity Reference
In Apache Calcite prior to version 1.32.0 the SQL operators 'EXISTS_NODE', 'EXTRACT_XML', 'XML_TRANSFORM' and 'EXTRACT_VALUE' do not restrict XML External Entity references in their configuration, which makes them vulnerable to a potential XML External Entity (XXE) attack. Therefore any client exposing these operators, typically by using Oracle dialect (the first three) or MySQL dialect (the last one), is affected by this vulnerability (the extent of it will depend on the user under which the application is running). From Apache Calcite 1.32.0 onwards, Document Type Declarations and XML External Entity resolution are disabled on the impacted operators.
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.