cgi/b on the BT Home Hub router allows remote attackers to bypass authentication and read or modify administrative settings or make arbitrary VoIP telephone calls by placing a character at the end of the PATH_INFO as demonstrated by (1) %5C (encoded backslash) (2) '%' (percent) and (3) '~' (tilde). NOTE: the '/' (slash) vector is already covered by CVE-2007-5383.