What’s Vulnerable › Vulnerabilities

CVE-2026-33210: Ruby JSON has a format string injection vulnerability

• Severity: critical (CVSS 9.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.9% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-03-20 · updated 2026-08-21
• Weakness: CWE-134

Description

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 products

• ruby json: from 2.14.0 before 2.15.2.1; from 2.16.0 before 2.17.1.2; from 2.18.0 before 2.19.2 — fixed in 2.15.2.1, 2.17.1.2, 2.19.2

How to fix

Upgrade to a fixed version: ruby json 2.15.2.1, 2.17.1.2, 2.19.2. Check the vendor advisory for mitigations.

References

• https://github.com/ruby/json/security/advisories/GHSA-3m6g-2423-7cp3
• https://access.redhat.com/errata/RHSA-2026:20596
• https://access.redhat.com/errata/RHSA-2026:20606
• https://access.redhat.com/errata/RHSA-2026:57565
• https://access.redhat.com/security/cve/CVE-2026-33210
• https://bugzilla.redhat.com/show_bug.cgi?id=2449871
• https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33210.json

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