In Artifex Ghostscript before 9.24, attackers able to supply crafted PostScript files could use a type confusion in the LockDistillerParams parameter to crash the interpreter or execute code.
https://www.kb.cert.org/vuls/id/332928
https://www.debian.org/security/2018/dsa-4288
https://usn.ubuntu.com/3768-1/
https://security.gentoo.org/glsa/201811-12
https://lists.debian.org/debian-lts-announce/2018/09/msg00015.html
https://kb.pulsesecure.net/articles/Pulse_Security_Advisories/SA44101