CVE-2009-3979: Mozilla Firefox

High severity, CVSS 9.3. EPSS: 4% chance of exploitation in the next 30 days.

Multiple unspecified vulnerabilities in the browser engine in Mozilla Firefox before 3.0.16 and 3.5.x before 3.5.6, SeaMonkey before 2.0.1, and Thunderbird allow remote attackers to cause a denial of service (memory corruption and application crash) or possibly execute arbitrary code via unknown vectors.

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; …

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