Heap-based buffer overflow in the thunder (aka ThunderScan) decoder in tif_thunder.c in LibTIFF 3.9.4 and earlier allows remote attackers to execute arbitrary code via crafted THUNDER_2BITDELTAS data in a .tiff file that has an unexpected BitsPerSample value.
The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.