In Artifex MuPDF 1.12.0, there is a heap-based buffer overflow vulnerability in the do_pdf_save_document function in the pdf/pdf-write.c file. Remote attackers could leverage the vulnerability to cause a denial of service via a crafted pdf file.
https://www.debian.org/security/2018/dsa-4334
https://security.gentoo.org/glsa/201811-15