ext/phar/phar_object.c in PHP before 5.5.32, 5.6.x before 5.6.18, and 7.x before 7.0.3 mishandles zero-length uncompressed data, which allows remote attackers to cause a denial of service (heap memory corruption) or possibly have unspecified other impact via a crafted (1) TAR, (2) ZIP, or (3) PHAR archive.