A use-after-free vulnerability exists in libxml2 versions before 2.12.10 and 2.13.x before 2.13.6 in the functions xmlSchemaIDCFillNodeTables and xmlSchemaBubbleIDCNodeTables. Exploitation requires processing a crafted XML document against an XML schema with specific identity constraints or using a crafted XML schema. The vulnerability has a high severity score of 7.8 and can lead to a complete compromise of confidentiality and integrity without availability impact.