US-CERT is aware of reports stating that multiple programming language implementations, including web platforms, are vulnerable to hash table collision attacks. This vulnerability could be used by an attacker to launch a denial-of-service attack against websites using affected products.
The Ruby Security Team has updated Ruby 1.8.7. The Ruby 1.9 series is not affected by this attack. Additional information can be found in the ruby 1.8.7 patchlevel 357 release notes.
Microsoft has released an update for the .NET Framework to address this vulnerability and three others. Additional information can be found in Microsoft Security Bulletin MS11-100 and Microsoft Security Advisory 2659883.
More information regarding this vulnerability can be found in US-CERT Vulnerability Note VU#903934 and n.runs Security Advisory n.runs-SA-2011.004.
US-CERT will provide additional information as it becomes available.