ImageMagick has a possible stack buffer overflow in sixel encoder

ImageMagick is free and open-source software used for editing and manipulating digital images. Prior to 7.1.2-16 and 6.9.13-41, when a memory allocation fails in the sixel encoder it would be possible to write past the end of a buffer on the stack. This vulnerability is fixed in 7.1.2-16 and 6.9.13-41.