CVE-2009-1305: Mozilla Firefox

Medium severity, CVSS 5.0. EPSS: 1.9% chance of exploitation in the next 30 days.

The JavaScript engine in Mozilla Firefox before 3.0.9, Thunderbird before 2.0.0.22, and SeaMonkey before 1.1.16 allows remote attackers to cause a denial of service (application crash) and possibly trigger memory corruption via vectors involving JSOP_DEFVAR and properties that lack the JSPROP_PERMANENT attribute.

Affected products

• Mozilla Firefox: version 3.0 only; version 3.0.1 only; version 3.0.2 only; version 3.0.3 only; version 3.0.4 only; version 3.0.5 only; …
• Mozilla Seamonkey: up to and including 1.1.13; 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 2.0.0.19; 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 2009-04-22. Last modified 2026-06-16.