---
id: CVE-2026-33210
title: Ruby JSON is a JSON implementation for Ruby
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_d…
severity: critical
cvss: 9.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H'
cwe:
  - CWE-134
  - CWE-134
vendor: ruby-lang
product: json
affected:
  - 'json >= 2.14.0, < 2.15.2.1'
  - 'json >= 2.16.0, < 2.17.1.2'
  - 'json >= 2.18.0, < 2.19.2'
patched:
  - json 2.19.2
published: '2026-03-20'
updated: '2026-07-21'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-33210'
references:
  - url: 'https://github.com/ruby/json/security/advisories/GHSA-3m6g-2423-7cp3'
    label: security-advisories@github.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:20596'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:20606'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/security/cve/CVE-2026-33210'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2449871'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33210.json
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
tags:
  - nvd
epss: 0.00857
epssPercentile: 0.56921
ingestedAt: '2026-07-21T16:51:40.390Z'
---

## Overview

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.

## Affected

- `json >= 2.14.0, < 2.15.2.1`
- `json >= 2.16.0, < 2.17.1.2`
- `json >= 2.18.0, < 2.19.2`

## Remediation

Upgrade past the affected range:

- `json 2.19.2`