LibTIFF 4.0.7 has an "outside the range of representable values of type unsigned char" undefined behavior issue, which might allow remote attackers to cause a denial of service (application crash) or possibly have unspecified other impact via a crafted image.
https://usn.ubuntu.com/3602-1/
https://security.gentoo.org/glsa/201709-27
https://blogs.gentoo.org/ago/2017/04/01/libtiff-multiple-ubsan-crashes