Remote code execution via HuffmanDecodeImage overflow

GraphicsMagick before 1.3.35 allows remote attackers to trigger a heap-based buffer overflow via a crafted image. HuffmanDecodeImage in magick/compress.c performs arithmetic that can overflow an integer before allocating or writing decoded Huffman data, allowing the write to exceed the heap buffer. Processing the malicious image can crash the service and, in the worst case, execute attacker-controlled code; the vulnerable parser must be reachable by an image-processing service or application.