CVE 2009-1855
Stack-based buffer overflow in Adobe Reader 7 and Acrobat 7 before 7.1.3, Adobe Reader 8 and Acrobat 8 before 8.1.6, and Adobe Reader 9 and Acrobat 9 before 9.1.2 might allow attackers to execute arbitrary code via a PDF file containing a malformed U3D model file with a crafted extension block.
See the 
CVE page on Mitre.org
for more details.
