CVE-2011-4838

Severity: medium (CVSS 5.0 v2.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 4.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2011-12-30 · updated 2026-06-16
Weakness: CWE-400

Description

JRuby before 1.6.5.1 computes hash values without restricting the ability to trigger hash collisions predictably, which allows context-dependent attackers to cause a denial of service (CPU consumption) via crafted input to an application that maintains a hash table.

Affected products

Jruby: before 1.6.5.1 — fixed in 1.6.5.1

How to fix

Upgrade to a fixed version: Jruby 1.6.5.1. Check the vendor advisory for mitigations.

References

http://archives.neohapsis.com/archives/bugtraq/2011-12/0181.html
http://jruby.org/2011/12/27/jruby-1-6-5-1.html
http://rhn.redhat.com/errata/RHSA-2012-1232.html
http://secunia.com/advisories/47407
http://secunia.com/advisories/50084
http://security.gentoo.org/glsa/glsa-201207-06.xml
http://www.kb.cert.org/vuls/id/903934
http://www.nruns.com/_downloads/advisory28122011.pdf
http://www.ocert.org/advisories/ocert-2011-003.html
https://exchange.xforce.ibmcloud.com/vulnerabilities/72019
http://archives.neohapsis.com/archives/bugtraq/2011-12/0181.html
http://jruby.org/2011/12/27/jruby-1-6-5-1.html

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