Ruby is an extensible, interpreted, object-oriented, scripting language. Ithas features to process text files and to do system management tasks.A denial of service flaw was found in the implementation of associativearrays (hashes) in Ruby. An attacker able to supply a large number ofinputs to a Ruby application (such as HTTP POST request parameters sent toa web application) that are used as keys when inserting data into an arraycould trigger multiple hash function collisions, making array operationstake an excessive amount of CPU time. To mitigate this issue, randomizationhas been added to the hash function to reduce the chance of an attackersuccessfully causing intentional collisions. (CVE-2011-4815)Red Hat would like to thank oCERT for reporting this issue. oCERTacknowledges Julian Wälde and Alexander Klink as the original reporters.All users of ruby are advised to upgrade to these updated packages, whichcontain a backported patch to resolve this issue.