ImageMagick has a stack write buffer overflow in MNG encoder

ImageMagick is free and open-source software used for editing and manipulating digital images. Prior to versions 7.1.2-16 and 6.9.13-41, a stack buffer overflow vulnerability exists in the MNG encoder. There is a bounds checks missing that could corrupting the stack with attacker-controlled data. This vulnerability is fixed in 7.1.2-16 and 6.9.13-41.