Two vulnerabilities were identified in the Ruby language interpreter, version 1.9.1.
Jean-Philippe Aumasson identified that Ruby computed hash values without properly restricting the ability to trigger hash collisions predictably, allowing context-dependent attackers to cause a denial of service (CPU consumption). This is a different vulnerability than CVE-2011-4815.
Thomas Hollstegge and Ben Murphy found that the JSON gem for Ruby allowed remote attackers to cause a denial of service (resource consumption) or bypass the mass assignment protection mechanism via a crafted JSON document that triggers the creation of arbitrary Ruby symbols or certain internal objects.
For the squeeze distribution, theses vulnerabilities have been fixed in version 220.127.116.11-2+deb6u5 of ruby1.9.1. We recommend that you upgrade your ruby1.9.1 package.