ImageMagick before 6.9.11-40 and 7.x before 7.0.10-40 mishandles the -authenticate option, which allows setting a password for password-protected PDF files. The user-controlled password was not properly escaped/sanitized and it was therefore possible to inject additional shell commands via coders/pdf.c.
https://security.gentoo.org/glsa/202101-36
https://lists.debian.org/debian-lts-announce/2023/03/msg00008.html
https://lists.debian.org/debian-lts-announce/2021/01/msg00010.html
https://insert-script.blogspot.com/2020/11/imagemagick-shell-injection-via-pdf.html