PHP is a general-purpose scripting language widely used to develop web-based applications. It can run on a web server with the mod_php module or the CGI version and also stand-alone in a CLI.
Stefan Esser of the Hardened PHP project has reported a few vulnerabilities found in PHP:
By sending a specially crafted request, a remote attacker can exploit this vulnerability to inject arbitrary HTTP headers, which will be included in the response sent to the user. The format string vulnerability may be exploited to execute arbitrary code.
There is no known workaround at this time.
All PHP 5.x users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=dev-lang/php-5.1.2"
All PHP 4.x users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=dev-lang/php-4.4.2"