A memory allocation failure was discovered in the ReadPNMImage function in coders/pnm.c in GraphicsMagick 1.3.26. The vulnerability causes a big memory allocation, which may lead to remote denial of service in the MagickRealloc function in magick/memory.c.
Ubuntu Security Notice 4206-1 - It was discovered that GraphicsMagick incorrectly handled certain image files. An attacker could possibly use this issue to cause a denial of service.