Pillow is a Python imaging library. From 9.2.0 until 13.0.0, Pillow performs quadratic copying when saving a GIF with a long comment. get global header() repeatedly copies portions of comment data while assembling the global header, including comments retained from an untrusted input image. An attacker can supply an image with a large GIF comment to an application that saves it as GIF. This can consume excessive CPU and delay or deny service. This issue is fixed in version 13.0.0.