Apache Httpd < 2.4.25: HTTP_PROXY environment variable "httpoxy" mitigation

2016-07-02T00:00:00
ID HTTPD:CE14FA5A5B1A2BE3A35EA809C9D8CFF7
Type httpd
Reporter We would like to thank Dominic Scheirlinck and Scott Geary of Vend for reporting and proposing a fix for this issue.
Modified 2016-12-20T00:00:00

Description

HTTP_PROXY is a well-defined environment variable in a CGI process, which collided with a number of libraries which failed to avoid colliding with this CGI namespace. A mitigation is provided for the httpd CGI environment to avoid populating the "HTTP_PROXY" variable from a "Proxy:" header, which has never been registered by IANA.

This workaround and patch are documented in the ASF Advisory at https://www.apache.org/security/asf-httpoxy-response.txt and incorporated in the 2.4.25 release.

Note: This is not assigned an httpd severity, as it is a defect in other software which overloaded well-established CGI environment variables, and does not reflect an error in HTTP server software.