CVE-2004-0765: Mozilla Firefox

High severity, CVSS 7.5. EPSS: 1% chance of exploitation in the next 30 days.

The cert_TestHostName function in Mozilla before 1.7, Firefox before 0.9, and Thunderbird before 0.7, only checks the hostname portion of a certificate when the hostname portion of the URI is not a fully qualified domain name (FQDN), which allows remote attackers to spoof trusted certificates.

Affected products

• Mozilla Firefox: up to and including 0.9
• Mozilla Mozilla: up to and including 1.7
• Mozilla Thunderbird: up to and including 0.7

Published 2004-08-18. Last modified 2026-06-16.