CVE 2009-3389
Integer overflow in libtheora in Xiph.Org Theora before 1.1, as used in Mozilla Firefox 3.5 before 3.5.6 and SeaMonkey before 2.0.1, allows remote attackers to cause a denial of service (application crash) or possibly execute arbitrary code via a video with large dimensions.
See the 
CVE page on Mitre.org
for more details.
