PHP Apache module 4.0.4 and earlier allows remote attackers to bypass .htaccess access restrictions via a malformed HTTP request on an unrestricted page that causes PHP to use those access controls on the next page that is requested.
https://exchange.xforce.ibmcloud.com/vulnerabilities/5940
http://www.securityfocus.com/bid/2206
http://www.redhat.com/support/errata/RHSA-2000-136.html
http://www.linux-mandrake.com/en/security/2001/MDKSA-2001-013.php3
http://www.debian.org/security/2001/dsa-020
http://marc.info/?l=bugtraq&m=97957961212852
http://distro.conectiva.com.br/atualizacoes/?id=a&anuncio=000373