psi/ztoken.c in Artifex Ghostscript 9.21 mishandles references to the scanner state structure, which allows remote attackers to cause a denial of service (application crash) or possibly have unspecified other impact via a crafted PostScript document, related to an out-of-bounds read in the igc_reloc_struct_ptr function in psi/igc.c.
https://security.gentoo.org/glsa/201811-12
https://bugs.ghostscript.com/show_bug.cgi?id=698158
http://www.securitytracker.com/id/1039233
http://www.debian.org/security/2017/dsa-3986
http://git.ghostscript.com/?p=ghostpdl.git%3Ba=commit%3Bh=671fd59eb657743aa86fbc1895cb15872a317caa