CVE 2011-2377
Mozilla Firefox before 3.6.18 and 4.x through 4.0.1, Thunderbird before 3.1.11, and SeaMonkey through 2.0.14 allow remote attackers to cause a denial of service (memory corruption and application crash) or possibly execute arbitrary code via a multipart/
See the 
CVE page on Mitre.org
for more details.
