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Fencer Vulns
critical 9.1

CVE-2026-33210 json

Ruby JSON has a format string injection vulnerability

published 2026-03-19 7 mo ago modified 2026-09-10 1 mo ago also EUVD-2026-13875 , GHSA-3m6g-2423-7cp3

cvss
9.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.9%
EPSS 0.9% chance of exploitation in 30 days, percentile 59%
public exploits
0
none known

Summary

Ruby JSON is a JSON implementation for Ruby. From version 2.14.0 to before versions 2.15.2.1, 2.17.1.2, and 2.19.2, a format string injection vulnerability can lead to denial of service attacks or information disclosure, when the allow_duplicate_key: false parsing option is used to parse user supplied documents. This issue has been patched in versions 2.15.2.1, 2.17.1.2, and 2.19.2.

Patch / fix

  • rubygems json 2.15.2.1, 2.17.1.2, 2.19.2
  • Red Hat Red Hat Enterprise Linux 10 0:4.0.3-34.el10_2
  • Red Hat Red Hat Enterprise Linux 9 9080020260513131334.9
  • Red Hat Red Hat Hardened Images 4.0.6-37.2.hum1
  • ruby-json Debian 14 2.19.2+dfsg-1

debian advisories DEBIAN-CVE-2026-33210

  • ruby4.0 hummingbird 1 4.0.6-37.2.hum1
  • ruby4.0-libs hummingbird 1 4.0.6-37.2.hum1
  • rubygem4.0-irb hummingbird 1 1.16.0-37.2.hum1
  • rubygem4.0-rbs hummingbird 1 3.10.0-37.2.hum1
  • rubygem4.0-rss hummingbird 1 0.3.2-37.2.hum1
  • rubygem4.0-json hummingbird 1 2.18.0-37.2.hum1
  • rubygem4.0-racc hummingbird 1 1.8.1-37.2.hum1
  • rubygem4.0-rake hummingbird 1 13.3.1-37.2.hum1

red hat advisories RHSA-2026:57565RHSA-2026:20606RHSA-2026:20596

  • ruby AlmaLinux 9 4.0.3-32.module_el9.8.0+251+5fdbd96b
  • rubygems AlmaLinux 9 4.0.6-32.module_el9.8.0+251+5fdbd96b
  • ruby-libs AlmaLinux 9 4.0.3-32.module_el9.8.0+251+5fdbd96b
  • rubygem-pg AlmaLinux 9 1.6.3-1.module_el9.8.0+232+50f6dd36
  • rubygem-irb AlmaLinux 9 1.16.0-32.module_el9.8.0+251+5fdbd96b
  • rubygem-rbs AlmaLinux 9 3.10.0-32.module_el9.8.0+251+5fdbd96b
  • rubygem-rss AlmaLinux 9 0.3.2-32.module_el9.8.0+251+5fdbd96b
  • rubygem-json AlmaLinux 9 2.18.0-32.module_el9.8.0+251+5fdbd96b

almalinux advisories ALSA-2026:20596ALSA-2026:20606

  • ruby4.0 Rocky Linux 10 4.0.3-34.el10_2
  • rubygem-pg Rocky Linux 9 1.6.3-1.module+el9.8.0+40094+ce01217c
  • rubygem-mysql2 Rocky Linux 9 0.5.7-1.module+el9.8.0+40094+ce01217c

rocky linux advisories RLSA-2026:20606RLSA-2026:20596

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-2026-33210 updated cvss 9.1

ruby/json: Ruby JSON: Denial of Service or Information Disclosure via format string injection

  • Red Hat Enterprise Linux AppStream (v. 9) ruby 4.0.3-32.module+el9.8.0+24280+122d8796, rubygems 4.0.6-32.module+el9.8.0+24280+122d8796, ruby-libs 4.0.3-32.module+el9.8.0+24280+122d8796, rubygem-pg 1.6.3-1.module+el9.8.0+24280+122d8796, rubygem-rss 0.3.2-32.module+el9.8.0+24280+122d8796, rubygem-irb 1.16.0-32.module+el9.8.0+24280+122d8796, +17 more
    fixed: vendor fix RHSA-2026:20596
  • Red Hat Enterprise Linux AppStream (v. 10) ruby4.0 4.0.3-34.el10_2, ruby4.0-rubygem-pg 1.6.3-34.el10_2, ruby4.0-rubygem-mysql2 0.5.7-34.el10_2 Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) ruby4.0-doc 4.0.3-34.el10_2
    fixed: vendor fix RHSA-2026:20606
  • Red Hat Hardened Images ruby4.0 4.0.6-37.2.hum1, ruby4.0-libs 4.0.6-37.2.hum1, rubygem4.0-rss 0.3.2-37.2.hum1, rubygem4.0-irb 1.16.0-37.2.hum1, rubygem4.0-racc 1.8.1-37.2.hum1, rubygem4.0-rbs 3.10.0-37.2.hum1, +15 more
    fixed: vendor fix RHSA-2026:57565
  • Red Hat Logging Subsystem for Red Hat OpenShift openshift-logging/vector-rhel9, openshift-logging/fluentd-rhel9, openshift-logging/eventrouter-rhel9, openshift-logging/logging-view-plugin-rhel9, openshift-logging/cluster-logging-rhel9-operator, openshift-logging/log-file-metric-exporter-rhel9, +1 more Red Hat 3scale API Management Platform 2 3scale-amp21/zync, 3scale-amp22/zync, 3scale-amp24/zync, 3scale-amp25/zync, 3scale-amp26/zync, 3scale-amp20/system, +19 more Red Hat AMQ Clients json Red Hat Enterprise Linux 8 pcs, ruby, pcs-snmp, ruby-irb, rubygems, ruby-libs, +27 more Red Hat Enterprise Linux 9 ruby, rubygems, ruby-libs, rubygem-irb, rubygem-rbs, rubygem-rss, +13 more Red Hat Enterprise Linux 10 ruby
    +1 more products
    Red Hat Enterprise Linux AI (RHEL AI) 3 json
    not affected: vulnerable code not present

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

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
7 mo ago

Exploit prediction

0.89% chance of exploitation in the next 30 days, higher than 59% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 8.3 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N
CISA ADP 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
CNA 4.0 8.3 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
CNA 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Affected packages

ecosystem package affected fixed in
rubygems json
>=2.18.0, <2.19.2
>=2.16.0, <2.17.1.2
>=2.14.0, <2.15.2.1
2.19.2
2.17.1.2
2.15.2.1

Affected products

  • ruby json
  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Enterprise Linux 9
  • Red Hat Red Hat Hardened Images
  • Red Hat Logging Subsystem for Red Hat OpenShift
  • Red Hat Red Hat 3scale API Management Platform 2
  • Red Hat Red Hat AMQ Clients
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux AI (RHEL AI) 3

Classification

Weakness
  • CWE-134 Use of Externally-Controlled Format String

References

Sources

Fencer Vulns 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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.