The Internationalized Domain Names (IDN) blacklist in Mozilla Firefox 3.0.6 and other versions before 3.0.9; Thunderbird before 2.0.0.21; and SeaMonkey before 1.1.15 does not include box-drawing characters, which allows remote attackers to spoof URLs and conduct phishing attacks, as demonstrated by homoglyphs of the / (slash) and ? (question mark) characters in a subdomain of a .cn domain name, a different vulnerability than CVE-2005-0233. NOTE: some third parties claim that 3.0.6 is not affected, but much older versions perhaps are affected.

The International Domain Name (IDN) support in Firefox 1.0, Camino .8.5, and Mozilla before 1.7.6 allows remote attackers to spoof domain names using punycode encoded domain names that are decoded in URLs and SSL certificates in a way that uses homograph characters from other character sets, which facilitates phishing attacks.