Description
A denial of service flaw was found in the implementation of associative
arrays (hashes) in Ruby. An attacker able to supply a large number of
inputs to a Ruby application (such as HTTP POST request parameters sent to
a web application) that are used as keys when inserting data into an array
could trigger multiple hash function collisions, making array operations
take an excessive amount of CPU time. To mitigate this issue, randomization
has been added to the hash function to reduce the chance of an attacker
successfully causing intentional collisions. (CVE-2011-4815)