Nginx HTTP request Buffer Underflow and Denial of Service

This strike exploits a buffer underflow vulnerability in the nginx HTTP server. The underflow can occur when parsing HTTP requests that contain directory traversals. When a "../" sequence occurs, the code does not validate all cases where the parent directory search starts from the root directory. If the request begins with the string "/%23../" "//../", or "/%3F../", the code will search for the "/" character backwards in the heap memory. If found, the data following the request will then be copied to the heap space after it, corrupting memory and potentially terminating the http server.