An issue was discovered in LibTIFF 4.0.9. There are two out-of-bounds writes in cpTags in tools/tiff2bw.c and tools/pal2rgb.c, which can cause a denial of service (application crash) or possibly have unspecified other impact via a crafted image file.
https://www.debian.org/security/2018/dsa-4349
https://usn.ubuntu.com/3906-2/
https://usn.ubuntu.com/3864-1/
https://lists.debian.org/debian-lts-announce/2018/10/msg00019.html
https://access.redhat.com/errata/RHSA-2019:2053