In ImageMagick 7.0.6-8, the WritePDFImage function in coders/pdf.c operates on an incorrect data structure in the "dump uncompressed PseudoColor packets" step, which allows attackers to cause a denial of service (assertion failure in WriteBlobStream in MagickCore/blob.c) via a crafted file.
https://security.gentoo.org/glsa/201711-07