Is CVE-2026-33210 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-33210 being exploited in the wild.

How severe is CVE-2026-33210?

Critical severity, with a CVSS score of 9.1, published 20 March 2026.

Which products and versions are affected?

Red Hat Enterprise Linux AppStream 9, 10; json (RubyGems) ECOSYSTEM:introduced=2.18.0,fixed=2.19.2.

Is there a fix for CVE-2026-33210?

Yes. json (RubyGems): upgrade to 2.19.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-33210 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-33210?

Check whether you run Red Hat Enterprise Linux AppStream or json (RubyGems) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-33210: Ruby JSON format string injection in JSON parser

CVE-2026-33210 · Severity: critical · CVSS 9.1 · Published 2026-03-20

The Ruby JSON library, a widely used tool for processing data in Ruby applications, contains a security flaw when handling specific parsing options. If an application is configured to reject duplicate keys in JSON documents, an attacker can send a specially crafted file to crash the service or potentially view sensitive internal information. This could lead to service outages or unauthorized data exposure for any application using the affected library versions.

Technologies: Red Hat Enterprise Linux AppStream, json (RubyGems). Vendors: Red Hat, RubyGems.

Quick answers

Is CVE-2026-33210 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-33210 being exploited in the wild.
How severe is CVE-2026-33210?: Critical severity, with a CVSS score of 9.1, published 20 March 2026.
Which products and versions are affected?: Red Hat Enterprise Linux AppStream 9, 10; json (RubyGems) ECOSYSTEM:introduced=2.18.0,fixed=2.19.2.
Is there a fix for CVE-2026-33210?: Yes. json (RubyGems): upgrade to 2.19.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-33210 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-33210?: Check whether you run Red Hat Enterprise Linux AppStream or json (RubyGems) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

json (RubyGems): upgrade to 2.19.2 or later
```
bundle update json
```

Technical details

A format string injection vulnerability (CWE-134) exists in the Ruby JSON gem between versions 2.14.0 and 2.19.2. The issue is triggered when the parser is explicitly configured with the 'allow_duplicate_key: false' option (which is not the default) and processes untrusted JSON documents. An attacker can provide malicious input that is interpreted as a format string, allowing for unauthorized memory reads (information disclosure) or application crashes (denial of service). The vulnerability has been patched in versions 2.15.2.1, 2.17.1.2, and 2.19.2. Users can mitigate the risk by ensuring the 'allow_duplicate_key' option is set to true or by upgrading to a patched version.

Affected products

ruby json >= 2.14.0, < 2.15.2.1; >= 2.16.0, < 2.17.1.2; >= 2.18.0, < 2.19.2
Red Hat Enterprise Linux AppStream 9, 10

Identifiers

CVE-2026-33210
GHSA-3m6g-2423-7cp3

Timeline

2026-03-18: advisory: GitHub Security Advisory published
2026-03-20: disclosed: CVE published to NVD
2026-05-26: patched: Red Hat released security updates for RHEL 9

References

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