CVE-2009-3984: Mozilla Firefox

Medium severity, CVSS 6.8. EPSS: 2.2% chance of exploitation in the next 30 days.

Mozilla Firefox before 3.0.16 and 3.5.x before 3.5.6, and SeaMonkey before 2.0.1, allows remote attackers to spoof an SSL indicator for an http URL or a file URL by setting document.location to an https URL corresponding to a site that responds with a No Content (aka 204) status code and an empty body.

Affected products

• Mozilla Firefox: up to and including 3.0.15; version 0.1 only; version 0.2 only; version 0.3 only; version 0.4 only; version 0.5 only; …
• Mozilla Seamonkey: up to and including 2.0; 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 Thunderbird: any version

Published 2009-12-17. Last modified 2026-06-16.