xpdf -- multiple stack overflows in makeFileKey2();

Remote exploitation of a buffer overflow vulnerability in the xpdf PDF viewer included in multiple Unix and Linux distributions could allow for arbitrary code execution as the user viewing a PDF file.

The vulnerability specifically exists due to insufficient bounds checking while processing a PDF file that provides malicious values in the /Encrypt /Length tag. The offending code can be found in the Decrypt::makeFileKey2 function in the source file xpdf/Decrypt.cc.