CVE-2009-3978: Mozilla Firefox

Medium severity, CVSS 4.3. EPSS: 1.8% chance of exploitation in the next 30 days.

The nsGIFDecoder2::GifWrite function in decoders/gif/nsGIFDecoder2.cpp in libpr0n in Mozilla Firefox before 3.5.5 allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) via an animated GIF file with a large image size, a different vulnerability than CVE-2009-3373.

Affected products

• Mozilla Firefox: up to and including 3.5.4; version 0.1 only; version 0.2 only; version 0.3 only; version 0.4 only; version 0.5 only; …

Published 2009-11-19. Last modified 2026-06-16.