GHSA-CP9V-662Q-VVX9 Pillow: NULL pointer dereference in Image.merge via an unvalidated band 0

Summary Image.merge checks the mode of every input band except band 0. If band 0 is a single-band I or F image, the native merge routine reads a pixel pointer that is NULL for those modes and the process crashes. The IPTC plugin reaches this from a plain Image.open followed by a load, and IPTC ha...