gdImageColorMatch in gd_color_match.c in the GD Graphics Library (aka LibGD) 2.2.5, as used in the imagecolormatch function in PHP before 5.6.40, 7.x before 7.1.26, 7.2.x before 7.2.14, and 7.3.x before 7.3.1, has a heap-based buffer overflow. This can be exploited by an attacker who is able to trigger imagecolormatch calls with crafted image data.
https://www.debian.org/security/2019/dsa-4384
https://usn.ubuntu.com/3900-1/
https://security.netapp.com/advisory/ntap-20190315-0003/
https://security.gentoo.org/glsa/201903-18
https://lists.debian.org/debian-lts-announce/2019/01/msg00028.html
https://access.redhat.com/errata/RHSA-2019:3299
https://access.redhat.com/errata/RHSA-2019:2519
http://www.securityfocus.com/bid/106731
http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00031.html
http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00025.html