CVE-2020-27771

In RestoreMSCWarning() of /coders/pdf.c there are several areas where calls
to GetPixelIndex() could result in values outside the range of
representable for the unsigned char type. The patch casts the return value
of GetPixelIndex() to ssize_t type to avoid this bug. This undefined
behavior could be triggered when ImageMagick processes a crafted pdf file.
Red Hat Product Security marked this as Low severity because although it
could potentially lead to an impact to application availability, no
specific impact was demonstrated in this case. This flaw affects
ImageMagick versions prior to 7.0.9-0.

Bugs

• <https://github.com/ImageMagick/ImageMagick/issues/1753&gt;