In Artifex Ghostscript 9.23 before 2018-08-24, attackers able to supply crafted PostScript could use uninitialized memory access in the aesdecode operator to crash the interpreter or potentially 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