Buffer overflow in the International Domain Name (IDN) support in Mozilla Firefox 1.0.6 and earlier, and Netscape 8.0.3.3 and 7.2, allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a hostname with all "soft" hyphens (character 0xAD), which is not properly handled by the NormalizeIDN call in nsStandardURL::BuildNormalizedSpec.