CVE 2005-0592
Heap-based buffer overflow in the UTF8ToNewUnicode function for Firefox before 1.0.1 and Mozilla before 1.7.6 might allow remote attackers to cause a denial of service (crash) or execute arbitrary code via invalid sequences in a UTF8 encoded string that result in a zero length value.
See the 
CVE page on Mitre.org
for more details.
