Heap-based buffer overflow in the JBIG2 filter 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 allows remote attackers to cause a denial of service (memory corruption) or possibly execute arbitrary code via a crafted PDF file that contains JBIG2 text region segments with Huffman encoding.