Moderate severity vulnerability that affects rails

The session fixation protection mechanism in cgi_process.rb in
Rails 1.2.4, as used in Ruby on Rails, removes the :cookie_only
attribute from the DEFAULT_SESSION_OPTIONS constant, which
effectively causes cookie_only to be applied only to the first
instantiation of CgiRequest, which allows remote attackers to
conduct session fixation attacks.

NOTE: this is due to an incomplete fix for CVE-2007-5380.