gd_gif_in.c in the GD Graphics Library (aka libgd), as used in PHP before 5.6.33, 7.0.x before 7.0.27, 7.1.x before 7.1.13, and 7.2.x before 7.2.1, has an integer signedness error that leads to an infinite loop via a crafted GIF file, as demonstrated by a call to the imagecreatefromgif or imagecreatefromstring PHP function. This is related to GetCode_ and gdImageCreateFromGifCtx.
php.net/ChangeLog-5.php
php.net/ChangeLog-7.php
access.redhat.com/errata/RHSA-2018:1296
access.redhat.com/errata/RHSA-2019:2519
bugs.php.net/bug.php?id=75571
lists.debian.org/debian-lts-announce/2018/01/msg00022.html
lists.debian.org/debian-lts-announce/2019/01/msg00028.html
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3CZ2QADQTKRHTGB2AHD7J4QQNDLBEMM6/
security.gentoo.org/glsa/201903-18
usn.ubuntu.com/3755-1/
www.oracle.com/security-alerts/cpuapr2020.html