Ruby (aka CRuby) 1.9 before 1.9.3-p327 and 2.0 before r37575 computes hash values without properly restricting the ability to trigger hash…

published 2012-11-28 13 y ago modified 2026-06-16 4 mo ago also EUVD-2012-5290

cvss: 5.0; version 2.0, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 3.3%; EPSS 3.3% chance of exploitation in 30 days, percentile 88%
public exploits: 0; none known

Ruby (aka CRuby) 1.9 before 1.9.3-p327 and 2.0 before r37575 computes hash values without properly 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, as demonstrated by a universal multicollision attack against a variant of the MurmurHash2 algorithm, a different vulnerability than CVE-2011-4815.

Patch / fix

distros 1 links 3

ruby4.0 hummingbird 1 4.0.0-33.3.hum1
ruby4.0-libs hummingbird 1 4.0.0-33.3.hum1
ruby4.0-bundled-gems hummingbird 1 4.0.0-33.3.hum1
ruby4.0-default-gems hummingbird 1 4.0.0-33.3.hum1
ruby3.3 hummingbird 1 3.3.10-23.1.hum1
ruby3.3-libs hummingbird 1 3.3.10-23.1.hum1
ruby3.3-bundled-gems hummingbird 1 3.3.10-23.1.hum1
ruby3.3-default-gems hummingbird 1 3.3.10-23.1.hum1

red hat advisories RHSA-2026:8838 RHSA-2026:7305 RHSA-2026:7307 RHSA-2013:0582

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2012-5371 updated 2026-04-20 cvss 5.0

ruby: Murmur hash-flooding DoS flaw in ruby 1.9 (oCERT-2012-001)

Red Hat Hardened Images ruby
affected: no fix available
Red Hat Hardened Images ruby3.4 3.4.8-31.1.hum1, ruby4.0 4.0.0-33.3.hum1, ruby3.3 3.3.10-23.1.hum1, ruby3.4-default-gems 3.4.8-31.1.hum1, ruby4.0-default-gems 4.0.0-33.3.hum1, ruby3.3-default-gems 3.3.10-23.1.hum1
fixed: vendor fix RHSA-2026:7305
Red Hat OpenShift Enterprise Infrastructure graphviz 2.26.0-10.el6, graphviz-gd 2.26.0-10.el6, rubygem-bson 1.8.1-2.el6op, graphviz-ruby 2.26.0-10.el6, rubygem-mongo 1.8.1-2.el6op, ruby193-ruby 1.9.3.327-25.el6, +25 more Red Hat OpenShift Enterprise JBoss EAP add-on openshift-origin-cartridge-jbosseap-6.0 1.0.4-1.el6op Red Hat OpenShift Enterprise Node php 5.3.3-22.el6, php-imap 5.3.3-22.el6, php-bcmath 5.3.3-22.el6, php-process 5.3.3-22.el6, php-mbstring 5.3.3-22.el6, rubygem-bson 1.8.1-2.el6op, +32 more
fixed: vendor fix RHSA-2013:0582

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

3.33% chance of exploitation in the next 30 days, higher than 88% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by	version	score	vector
NVD	2.0	5.0	AV:N/AC:L/Au:N/C:N/I:N/A:P

Classification

Weakness

CWE-310 Cryptographic Issues

References

securitytracker.com /id?1027747
vdb-entry, patch
ruby-lang.org /en/news/2012/11/09/ruby19-hashdos-cve-2012-5371/
patch, vendor-advisory
bugzilla.redhat.com /show_bug.cgi?id=875236
patch
ubuntu.com /usn/USN-1733-1
vendor-advisory
asfws12.files.wordpress.com /2012/11/asfws2012-jean_philippe_aumasson-martin_bosslet-hash_flooding_dos_reloaded.pdf
osvdb.org /87280
vdb-entry
securityfocus.com /bid/56484
vdb-entry
131002.net /data/talks/appsec12_slides.pdf
2012.appsec-forum.ch /conferences/#c17
secunia.com /advisories/51253
third-party-advisory
ocert.org /advisories/ocert-2012-001.html
exchange.xforce.ibmcloud.com /vulnerabilities/79993
vdb-entry

Sources

CVE List CVE-2012-5371
NVD CVE-2012-5371

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary