Published:2012/07/06  Last Updated:2012/07/06

Ruby hash table implementation vulnerable to denial-of-service


The hash table implementation in Ruby contains a denial-of-service (DoS) vulnerability.

Products Affected

  • Ruby versions prior to 1.8.7-p357
  • Ruby 1.9.x versions prior to 1.9.1


The hash table implementation in Ruby contains an issue, where it may intentionally create a series of strings whose hash values collide. As a result, a denial-of-service (DoS) attack may be conducted.


When processing a series of specially crafted strings, a denial-of-service (DoS) may occur.


Update the Software
Update to the latest version according to the information provided by the developer.


  1. US-CERT Vulnerability Note VU#903934
    Hash table implementations vulnerable to algorithmic complexity attacks

JPCERT/CC Addendum

This JVN publication was delayed to 2012/07/06 after the developer fix was developed. From the fiscal year 2011, JPCERT/CC is using a new vendor coordination procedure. This new procedure came from the recommendation of the fiscal year 2010 "Study Group on Information System Vulnerability Handling" aimed at more timely JVN publications.

Vulnerability Analysis by JPCERT/CC


Tanaka Akira of National Institute of Advanced Industrial Science and Technology (AIST) reported this vulnerability to IPA.
JPCERT/CC coordinated with the developer under Information Security Early Warning Partnership.

Other Information

JPCERT Reports
CERT Advisory
CPNI Advisory
CVE CVE-2011-4815
JVN iPedia JVNDB-2012-000066