ImageSharp Triggers an Infinite Loop in its GIF Decoder When Skipping Malformed Comment Extension Blocks

ImageSharp is a 2D graphics library. In versions below 2.1.11 and 3.0.0 through 3.1.10, a specially crafted GIF file containing a malformed comment extension block (with a missing block terminator) can cause the ImageSharp GIF decoder to enter an infinite loop while attempting to skip the block. This leads to a denial of service. Applications processing untrusted GIF input should upgrade to a patched version. This issue is fixed in versions 2.1.11 and 3.1.11.