exif_process_IFD_in_MAKERNOTE in ext/exif/exif.c in PHP before 5.6.37, 7.0.x before 7.0.31, and 7.1.x before 7.1.20, allows remote attackers to cause a denial of service via a crafted JPEG file.An issue was discovered in PHP before 5.6.37, 7.0.x before 7.0.31, and 7.1.x before 7.1.20. An Integer Overflow leads to a heap-based buffer over-read in exif_thumbnail_extract of exif.c.