CVE-2009-0773: Mozilla Firefox

High severity, CVSS 10.0. EPSS: 5.8% chance of exploitation in the next 30 days.

The JavaScript engine in Mozilla Firefox before 3.0.7, Thunderbird before 2.0.0.21, and SeaMonkey 1.1.15 allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via (1) a splice of an array that contains "some non-set elements," which causes jsarray.cpp to pass an incorrect argument to the ResizeSlots function, which triggers memory corruption; (2) vectors related to js_DecompileValueGenerator, jsopcode.cpp, __defineSetter__, and watch, which triggers an assertion failure or a segmentation fault; and (3) vectors related to gczeal, __defineSetter__, and watch, which triggers a hang.

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 2009-03-05. Last modified 2026-06-16.