CVE-2026-33210 — json
CVE-2026-33210 is a CWE-134 vulnerability in json. A fix is available for json — see the affected versions and patch details below.
Ruby JSON has a format string injection vulnerability
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-33210.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Real-World Exposure
json💎json💎jsonReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.
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 Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | json | ≥ 2.18.0&&< 2.19.2 | 2.19.2bundle update json --conservative |
| 💎RubyGems | json | ≥ 2.16.0&&< 2.17.1.2 | 2.17.1.2bundle update json --conservative |
| 💎RubyGems | json | ≥ 2.14.0&&< 2.15.2.1 | 2.15.2.1bundle update json --conservative |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for json, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update json to 2.19.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-33210 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-33210 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-33210. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
A format string injection flaw was identified in Ruby JSON. This vulnerability allows a remote attacker to cause a denial of service or disclose sensitive information when processing specially crafted user-supplied documents with the `allow_duplicate_key: false` parsing option enabled. Red Hat Enterprise Linux 9.9…
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux 10 | ruby4.0-0:4.0.3-34.el10_2 | RHSA-2026:20606 |
| Red Hat Enterprise Linux 9 | ruby:4.0-9080020260513131334.9 | RHSA-2026:20596 |
| Red Hat Hardened Images | ruby4-0-main-4.0.6-37.2.hum1 | RHSA-2026:57565 |
Frequently Asked Questions
Is CVE-2026-33210 in your dependencies?
O3 Security finds CVE-2026-33210 across RubyGems dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.