The exif_ifd_make_value function in exif.c in the EXIF extension in PHP before 5.4.34, 5.5.x before 5.5.18, and 5.6.x before 5.6.2 operates on floating-point arrays incorrectly, which allows remote attackers to cause a denial of service (heap memory corruption and application crash) or possibly execute arbitrary code via a crafted JPEG image with TIFF thumbnail data that is improperly handled by the exif_thumbnail function.
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.