ImageMagick is free and open-source software used for editing and manipulating digital images. Prior to versions 7.1.2-15 and 6.9.13-40, a signed integer overflow vulnerability in ImageMagick's SIXEL decoder allows an attacker to trigger memory corruption and denial of service when processing a maliciously crafted SIXEL image file. The vulnerability occurs during buffer reallocation operations where pointer arithmetic using signed 32-bit integers overflows. Versions 7.1.2-15 and 6.9.13-40 contain a patch.