The gdImageCreate function in the GD Graphics Library (aka libgd) before 2.2.4 allows remote attackers to cause a denial of service (system hang) via an oversized image.
https://github.com/libgd/libgd/commit/1846f48e5fcdde996e7c27a4bbac5d0aef183e4b
https://github.com/libgd/libgd/blob/gd-2.2.4/CHANGELOG.md