Pillow is a Python imaging library. From 4.1.0 until 13.0.0, Pillow's MSP RLE decoder can expand a small file into an unbounded in-memory buffer. The decoder writes run-length output to BytesIO without limiting expansion to the declared image size. An attacker can supply a crafted MSP image to an application that loads its pixels. This can exhaust memory and deny service even when the declared pixel count passes the decompression-bomb check. This issue is fixed in version 13.0.0.