In LibTIFF 4.0.9, there is an uncontrolled resource consumption in the TIFFSetDirectory function of tif_dir.c. Remote attackers could leverage this vulnerability to cause a denial of service via a crafted tif file. This occurs because the declared number of directory entries is not validated against the actual number of directory entries.
https://www.debian.org/security/2018/dsa-4349
https://usn.ubuntu.com/3606-1/
https://usn.ubuntu.com/3602-1/
https://lists.debian.org/debian-lts-announce/2018/07/msg00002.html
https://lists.debian.org/debian-lts-announce/2018/05/msg00022.html
https://gitlab.com/libtiff/libtiff/commit/473851d211cf8805a161820337ca74cc9615d6ef