The ReadSUNImage function in coders/sun.c in GraphicsMagick 1.3.26 has an issue where memory allocation is excessive because it depends only on a length field in a header. This may lead to remote denial of service in the MagickMalloc function in magick/memory.c.
Ubuntu Security Notice 4232-1 - It was discovered that GraphicsMagick incorrectly handled certain image files. An attacker could possibly use this issue to cause a denial of service or other unspecified impact.