xpdf -- makeFileKey2() buffer overflow vulnerability

An iDEFENSE Security Advisory reports:

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.