The Apache Xerces-C 3.0.0 to 3.2.3 XML parser contains a use-after-free error triggered during the scanning of external DTDs. This flaw has not been addressed in the maintained version of the library and has no current mitigation other than to disable DTD processing. This can be accomplished via the DOM using a standard parser feature, or via SAX using the XERCES_DISABLE_DTD environment variable.
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.