CVE 2006-3677
Mozilla Firefox 1.5 before 1.5.0.5 and SeaMonkey before 1.0.3 allows remote attackers to execute arbitrary code by changing certain properties of the window navigator object (window.navigator) that are accessed when Java starts up, which causes a crash that leads to code execution.
See the 
CVE page on Mitre.org
for more details.
