The phar_parse_zipfile function in zip.c in the PHAR extension in PHP before 5.5.33 and 5.6.x before 5.6.19 allows remote attackers to obtain sensitive information from process memory or cause a denial of service (out-of-bounds read and application crash) by placing a PK\x05\x06 signature at an invalid location.
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.