JsonApplication · Ruby Lang
CVE-2026-33210
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedRuby 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceFormat string injection vulnerability in Ruby JSON library versions 2.14.0 through 2.15.2.0, 2.17.1.1, and 2.19.1 allows attackers to cause denial of service or disclose information by supplying malicious JSON documents when the allow_duplicate_key: false parsing option is used.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
JsonApplication
>= 2.14.0, < 2.15.2.1>= 2.16.0, < 2.17.1.2>= 2.18.0, < 2.19.2CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify installed JSON gem versionRun 'gem list json' or add 'puts JSON::VERSION' in Ruby to print the versionAffected if The version falls within >= 2.14.0, < 2.15.2.1 OR >= 2.16.0, < 2.17.1.2 OR >= 2.18.0, < 2.19.2
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Search for allow_duplicate_key usageGrep your codebase for 'allow_duplicate_key' or 'allow_duplicate_key: false'Affected if Code uses JSON.parse with allow_duplicate_key: false option
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Check JSON parsing of external inputReview code paths where JSON.parse receives data from user requests, APIs, or untrusted sourcesAffected if Untrusted JSON input is parsed with allow_duplicate_key: false enabled
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Verify affected code execution in runtimeUse logging or debugging to confirm the vulnerable code path executes in your application flowAffected if The combination of vulnerable gem version AND allow_duplicate_key: false with untrusted input executes in your environment
You are affected if your environment runs a JSON gem version within the affected ranges AND uses allow_duplicate_key: false to parse untrusted JSON input.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped2.15.2.12.17.1.22.19.2
Upgrade Ruby JSON gem to version 2.15.2.1, 2.17.1.2, or 2.19.2 or later to patch the format string injection vulnerability.
2.19.2 (or the appropriate patched version for your major branch: 2.15.2.1 for 2.14.x-2.15.x, 2.17.1.2 for 2.16.x-2.17.x, or 2.19.2 for 2.18.x-2.19.x)
- Identify the current JSON gem version in your Ruby project by checking your Gemfile or running `gem list json`
- Run `gem install json` or `bundle update json` to upgrade to the latest fixed version
- Verify the upgrade was successful by running `gem list json` to confirm version 2.19.2 or later is installed
- If using Bundler, update your Gemfile.lock by running `bundle update json` to lock the fixed version
- Test your application to ensure JSON parsing with `allow_duplicate_key: false` option still functions correctly
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Json
Scoped from the published advisory
- Consultation1.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,664.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-33210 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-33210 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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