CVE 2008-5013
Mozilla Firefox 2.x before 2.0.0.18 and SeaMonkey 1.x before 1.1.13 do not properly check when the Flash module has been dynamically unloaded properly, which allows remote attackers to execute arbitrary code via a crafted SWF file that "dynamically unloads itself from an outside JavaScript function," which triggers an access of an expired memory address.
See the 
CVE page on Mitre.org
for more details.
