CVE 2010-1121
Mozilla Firefox 3.6.x before 3.6.3 does not properly manage the scopes of DOM nodes that are moved from one document to another, which allows remote attackers to conduct use-after-free attacks and execute arbitrary code via unspecified vectors involving improper interaction with garbage collection, as demonstrated by Nils during a Pwn2Own competition at CanSecWest 2010.
See the 
CVE page on Mitre.org
for more details.
