The gdImageScaleTwoPass function in gd_interpolation.c in the GD Graphics Library (aka libgd) before 2.2.0, as used in PHP before 5.6.12, uses inconsistent allocate and free approaches, which allows remote attackers to cause a denial of service (memory consumption) via a crafted call, as demonstrated by a call to the PHP imagescale function.
Integer signedness error in GD Graphics Library 2.1.1 (aka libgd or libgd2) allows remote attackers to cause a denial of service (crash) or potentially execute arbitrary code via crafted compressed gd2 data, which triggers a heap-based buffer overflow.
The GetCode_ function in gd_gif_in.c in GD 2.1.1 and earlier, as used in PHP before 5.5.21 and 5.6.x before 5.6.5, allows remote attackers to cause a denial of service (buffer over-read and application crash) via a crafted GIF image that is improperly handled by the gdImageCreateFromGif function.
The gdPngReadData function in libgd 2.0.34 allows user-assisted attackers to cause a denial of service (CPU consumption) via a crafted PNG image with truncated data, which causes an infinite loop in the png_read_info function in libpng.