Amazon Linux AMI Security Advisory: ALAS-2016-760
Advisory Release Date: 2016-10-27 17:00 Pacific
It was discovered that python-twisted-web used the value of the Proxy header from HTTP requests to initialize the HTTP_PROXY environment variable for CGI scripts, which in turn was incorrectly used by certain HTTP client implementations to configure the proxy for outgoing HTTP requests. A remote attacker could possibly use this flaw to redirect HTTP requests performed by a CGI script to an attacker-controlled proxy via a malicious HTTP request.
Run yum update python-twisted-web to update your system.