CVE-2012-5370: Medium severity ruby vulnerability

A denial of service flaw was found in the JRuby's Murmur hash function implementation. A specially-crafted set of keys could trigger Murmur hash function collisions, which degrade hash table items insert performance by changing hash table operations complexity from an expected/average O(n) to the worst case O(n^2). Reporters were able to find colliding strings efficiently using equivalent substrings.

As various web application frameworks for Ruby automatically pre-fill certain arrays with data from the HTTP request (such as GET or POST parameters) for Ruby web applications, a remote attacker could use this flaw to make the Ruby interpreter use an excessive amount of CPU time by sending a POST request with a large number parameters which hash to the same value.

A different vulnerability than CVE-2011-4838.

References: [1] http://www.openwall.com/lists/oss-security/2012/11/23/4 [2] http://www.ocert.org/advisories/ocert-2012-001.html [3] http://2012.appsec-forum.ch/conferences/#c17 [4] https://www.131002.net/data/talks/appsec12slides.pdf [5] http://asfws12.files.wordpress.com/2012/11/asfws2012-jeanphilippeaumasson-martinbosslet-hashfloodingdosreloaded.pdf