In ImageMagick 7.0.5-7 Q16, an assertion failure was found in the function LockSemaphoreInfo, which allows attackers to cause a denial of service via a crafted file.
https://github.com/ImageMagick/ImageMagick/issues/491
https://github.com/ImageMagick/ImageMagick/commit/01843366d6a7b96e22ad7bb67f3df7d9fd4d5d74