CVE 2009-1097
Multiple buffer overflows in Java SE Development Kit (JDK) and Java Runtime Environment (JRE) 6 Update 12 and earlier allow remote attackers to access files or execute arbitrary code via (1) a crafted PNG image that triggers an integer overflow during memory allocation for display on the splash screen, aka CR 6804996; and (2) a crafted GIF image from which unspecified values are used in calculation of offsets, leading to object-pointer corruption, aka CR 6804997.
See the 
CVE page on Mitre.org
for more details.
