Amazon Linux AMI Security Advisory: ALAS-2011-9
Advisory Release Date: 2011-10-31 18:19 Pacific
Advisory Updated Date: 2014-09-14 14:26 Pacific
It was discovered that the Apache HTTP Server did not properly validate the request URI for proxied requests. In certain configurations, if a reverse proxy used the ProxyPassMatch directive, or if it used the RewriteRule directive with the proxy flag, a remote attacker could make the proxy connect to an arbitrary server, possibly disclosing sensitive information from internal web servers not directly accessible to the attacker. (CVE-2011-3368)
It was discovered that mod_proxy_ajp incorrectly returned an "Internal Server Error" response when processing certain malformed HTTP requests, which caused the back-end server to be marked as failed in configurations where mod_proxy was used in load balancer mode. A remote attacker could cause mod_proxy to not send requests to back-end AJP (Apache JServ Protocol) servers for the retry timeout period or until all back-end servers were marked as failed. (CVE-2011-3348)
Run yum update httpd to update your system.