A null pointer dereference vulnerability was discovered in the libxml2. The issue occurs in the xmlSchematronFormatReport function when processing incorrect XPath expressions in Schematron schema reports, leading to undefined behavior and potential crashes.

If a SoapVar instance is created with a fully qualified name larger than 2G, this will cause a NULL pointer dereference resulting in a segmentation fault, leading to a denial of service.

Libxml versions prior to 2.13 cannot correctly handle a call to xmlNodeSetName() with a name longer than 2G. It will leave the node object in an invalid state with a NULL name. This later causes a NULL pointer dereference when using the name during message serialization.

This can be exploited if a SoapVar is created with a fully qualified name that is longer than 2G. This would be possible if some application code uses a namespace prefix from an untrusted source like from a remote SOAP service.