rack/file.rb (Rack::File) in Rack 1.5.x before 1.5.2 and 1.4.x before 1.4.5 allows attackers to access arbitrary files outside the intended root directory via a crafted PATH_INFO environment variable, probably a directory traversal vulnerability that is remotely exploitable, aka "symlink path traversals."

References

• https://nvd.nist.gov/vuln/detail/CVE-2013-0262
• rack/rack@6f237e4
• https://bugzilla.redhat.com/show_bug.cgi?id=909071
• https://bugzilla.redhat.com/show_bug.cgi?id=909072
• https://gist.github.com/rentzsch/4736940
• https://github.com/rack/rack/blob/master/lib/rack/file.rb#L56
• https://groups.google.com/forum/#!msg/rack-devel/bf937jPZxJM/1s6x95vIhmAJ
• https://groups.google.com/forum/#!msg/rack-devel/mZsuRonD7G8/DpZIOmMLbOgJ
• http://lists.opensuse.org/opensuse-updates/2013-03/msg00048.html
• https://github.com/rubysec/ruby-advisory-db/blob/master/gems/rack/CVE-2013-0262.yml