||From the CVE entries:
CVE-2008-3905 - resolv.rb in Ruby 1.8.5 and earlier, 1.8.6 before
1.8.6-p287, 1.8.7 before 1.8.7-p72, and 1.9 r18423 and earlier uses
sequential transaction IDs and constant source ports for DNS requests,
which makes it easier for remote attackers to spoof DNS responses, a
different vulnerability than CVE-2008-1447.
CVE-2008-3790 - The REXML module in Ruby 1.8.6 through 1.8.6-p287, 1.8.7
through 1.8.7-p72, and 1.9 allows context-dependent attackers to cause a
denial of service (CPU consumption) via an XML document with recursively
nested entities, aka an "XML entity explosion."
CVE-2008-3443 - The regular expression engine (regex.c) in Ruby 1.8.5 and
earlier, 1.8.6 through 1.8.6-p286, 1.8.7 through 1.8.7-p71, and 1.9 through
r18423 allows remote attackers to cause a denial of service (infinite loop
and crash) via multiple long requests to a Ruby socket, related to memory
allocation failure, and as demonstrated against Webrick.