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.
lists.apple.com/archives/security-announce/2009/May/msg00002.html
secunia.com/advisories/31430
secunia.com/advisories/32165
secunia.com/advisories/32219
secunia.com/advisories/32371
secunia.com/advisories/32372
secunia.com/advisories/33185
secunia.com/advisories/33398
secunia.com/advisories/35074
securityreason.com/securityalert/4158
support.apple.com/kb/HT3549
support.avaya.com/elmodocs2/security/ASA-2008-424.htm
www.debian.org/security/2009/dsa-1695
www.redhat.com/support/errata/RHSA-2008-0895.html
www.redhat.com/support/errata/RHSA-2008-0897.html
www.securityfocus.com/bid/30682
www.securitytracker.com/id?1021075
www.us-cert.gov/cas/techalerts/TA09-133A.html
www.vupen.com/english/advisories/2009/1297
exchange.xforce.ibmcloud.com/vulnerabilities/44688
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A9570
usn.ubuntu.com/651-1/
usn.ubuntu.com/691-1/
www.exploit-db.com/exploits/6239
www.redhat.com/archives/fedora-package-announce/2008-October/msg00259.html
www.redhat.com/archives/fedora-package-announce/2008-October/msg00299.html