Multiple use-after-free vulnerabilities in libxml2 2.5.10 2.6.16 2.6.26 2.6.27 and 2.6.32 and libxml 1.8.17 allow context-dependent attackers to cause a denial of service (application crash) via crafted (1) Notation or (2) Enumeration attribute types in an XML file as demonstrated by the Codenomicon XML fuzzing framework.