Scott Geary of VendHQ discovered that the Apache HTTPD server 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.
For Debian 7 Wheezy, this problem has been fixed in version
2.2.22-13+deb7u7.
We recommend that you upgrade your apache2 packages.
Further information about Debian LTS security advisories, how to apply
these updates to your system and frequently asked questions can be
found at: <https://wiki.debian.org/LTS>