CVE-2009-0652: Mozilla Firefox

Medium severity, CVSS 5.8. EPSS: 1.5% chance of exploitation in the next 30 days.

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.

Affected products

• Mozilla Firefox: up to and including 3.0.6; version 1.0 only; version 1.0.1 only; version 1.0.2 only; version 1.0.3 only; version 1.0.4 only; …
• Mozilla Seamonkey: up to and including 1.1.14; version 1.0 only; version 1.0.1 only; version 1.0.2 only; version 1.0.3 only; version 1.0.5 only; …
• Mozilla Thunderbird: up to and including 2.0.0.20; version 2.0.0.0 only; version 2.0.0.4 only; version 2.0.0.5 only; version 2.0.0.6 only; version 2.0.0.9 only; …

Published 2009-02-20. Last modified 2026-06-16.