xpm -- image decoding vulnerabilities

Chris Evans discovered several vulnerabilities in the libXpm
image decoder:

A stack-based buffer overflow in xpmParseColors
An integer overflow in xpmParseColors
A stack-based buffer overflow in ParsePixels and
ParseAndPutPixels

The X11R6.8.1 release announcement reads:

This version is purely a security release, addressing
multiple integer and stack overflows in libXpm, the X
Pixmap library; all known versions of X (both XFree86
and X.Org) are affected, so all users of X are strongly
encouraged to upgrade.