CVE-2026-33210: Json Ruby JSON Has A Format Vulnerability
HIGHCVE-2026-33210 is a HIGH ruby json has a format vulnerability (CWE-134: Use of Externally-Controlled Format String) affecting Json libraries in the RubyGems ecosystem. The issue involves ruby json has a format string injection vulnerability. Remediation is available by upgrading affected packages to version 2.19.2, 2.17.1.2, 2.15.2.1.
CVE-2026-33210 at a Glance
How to Fix CVE-2026-33210
To remediate this vulnerability, upgrade all affected Json dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
Upgrade json to 2.19.2Upgrade json to 2.17.1.2Upgrade json to 2.15.2.1Run the following command in your project directory to verify that all resolved dependencies use the patched release:
inspect dependencies for jsonHow to Check if You Are Affected
To determine whether your application is affected by CVE-2026-33210, inspect your project dependencies for Json:
inspect dependencies for jsonAnalyze the terminal output to locate any version of Json in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.19.2), your application is affected.
Note: Verify declared build manifests and deployed runtime container environments.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-134: Use of Externally-Controlled Format String, where the product uses a function that accepts a format string as an argument, but the format string originates from an external source. In Json, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
CVE-2026-33210 Affected Json Versions
3 component(s)References
Frequently Asked Questions
What is CVE-2026-33210?
Which Json versions are affected?
What version fixes CVE-2026-33210?
Is json affected?
What CWE is associated with CVE-2026-33210?
How can I check RubyGems dependencies for CVE-2026-33210?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-3m6g-2423-7cp3",
"modified" : "2026-03-25T18:24:34Z",
"published" : "2026-03-19T12:45:53Z",
"aliases" : [ "CVE-2026-33210" ],
"summary" : "Ruby JSON has a format string injection vulnerability",
"details" : "### Impact\n\nA format string injection vulnerability than that lead to denial of service attacks or information disclosure, when the `allow_duplicate_key: false` parsing option is used to parse user supplied documents. \n\nThis option isn't the default, if you didn't opt-in to use it, you are not impacted.\n\n### Patches\n\nPatched in `2.19.2`.\n\n### Workarounds\n\nThe issue can be avoided by not using the `allow_duplicate_key: false` parsing option.",
"severity" : [ {
"type" : "CVSS_V4",
"score" : "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "RubyGems",
"name" : "json"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "2.18.0"
}, {
"fixed" : "2.19.2"
} ]
} ]
}, {
"package" : {
"ecosystem" : "RubyGems",
"name" : "json"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "2.16.0"
}, {
"fixed" : "2.17.1.2"
} ]
} ]
}, {
"package" : {
"ecosystem" : "RubyGems",
"name" : "json"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "2.14.0"
}, {
"fixed" : "2.15.2.1"
} ]
} ]
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/ruby/json/security/advisories/GHSA-3m6g-2423-7cp3"
}, {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-33210"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/ruby/json"
}, {
"type" : "WEB",
"url" : "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/json/CVE-2026-33210.yml"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-134" ],
"severity" : "HIGH",
"github_reviewed" : true,
"github_reviewed_at" : "2026-03-19T12:45:53Z",
"nvd_published_at" : "2026-03-20T23:16:46Z"
}
}