CVE 2009-1571
Use-after-free vulnerability in the HTML parser in Mozilla Firefox 3.0.x before 3.0.18 and 3.5.x before 3.5.8, Thunderbird before 3.0.2, and SeaMonkey before 2.0.3 allows remote attackers to execute arbitrary code via unspecified method calls that attempt to access freed objects in low-memory situations.
See the 
CVE page on Mitre.org
for more details.
