The issue allows attackers to cause a denial-of-service, resulting in an application crash due to a heap-based buffer over-read, via a crafted TIFF image file. This is related to functions in LibTIFF, specifically `TIFFRewriteDirectory`, `TIFFWriteDirectory`, `TIFFWriteDirectorySec`, and `TIFFWriteDirectoryTagColormap` in tif dirwrite.c. The problem occurs because of an incomplete fix for a previous issue.