In ReadOneJNGImage in coders/png.c in GraphicsMagick 1.3.26, a Null Pointer Dereference occurs while transferring JPEG scanlines, related to a PixelPacket pointer.
hg.graphicsmagick.org/hg/GraphicsMagick?cmd=changeset%3Bnode=6fc54b6d2be8
hg.graphicsmagick.org/hg/GraphicsMagick?cmd=changeset%3Bnode=da135eaedc3b
www.securityfocus.com/bid/101607
lists.debian.org/debian-lts-announce/2018/08/msg00002.html
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PF62B5PJA2JDUOCKJGUQO3SPL74BEYSV/
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WHIKB4TP6KBJWT2UIPWL5MWMG5QXKGEJ/
sourceforge.net/p/graphicsmagick/bugs/518/
usn.ubuntu.com/4232-1/
www.debian.org/security/2018/dsa-4321