Buffer overflow in the apache_request_headers function in sapi/cgi/cgi_main.c in PHP 5.4.x before 5.4.3 allows remote attackers to cause a denial of service (application crash) via a long string in the header of an HTTP request.
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.