Directory traversal vulnerability in Apache HTTP Server and Tomcat 5.x before 5.5.22 and 6.x before 6.0.10 when using certain proxy modules (mod_proxy mod_rewrite mod_jk) allows remote attackers to read arbitrary files via a .. (dot dot) sequence with combinations of (1) \/\ (slash) (2) \\\\ (backslash) and (3) URL-encoded backslash (%5C) characters in the URL which are valid separators in Tomcat but not in Apache.