{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-33228","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","state":"PUBLISHED","assignerShortName":"GitHub_M","dateReserved":"2026-03-18T02:42:27.507Z","datePublished":"2026-03-20T23:06:48.485Z","dateUpdated":"2026-03-24T17:57:22.866Z"},"containers":{"cna":{"title":"flatted: Prototype Pollution via parse()","problemTypes":[{"descriptions":[{"cweId":"CWE-1321","lang":"en","description":"CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')","type":"CWE"}]}],"metrics":[{"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"HIGH","vulnIntegrityImpact":"HIGH","vulnAvailabilityImpact":"HIGH","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":8.9,"baseSeverity":"HIGH","vectorString":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P","version":"4.0"}}],"references":[{"name":"https://github.com/WebReflection/flatted/security/advisories/GHSA-rf6f-7fwh-wjgh","tags":["x_refsource_CONFIRM"],"url":"https://github.com/WebReflection/flatted/security/advisories/GHSA-rf6f-7fwh-wjgh"},{"name":"https://github.com/WebReflection/flatted/commit/885ddcc33cf9657caf38c57c7be45ae1c5272802","tags":["x_refsource_MISC"],"url":"https://github.com/WebReflection/flatted/commit/885ddcc33cf9657caf38c57c7be45ae1c5272802"},{"name":"https://github.com/WebReflection/flatted/releases/tag/v3.4.2","tags":["x_refsource_MISC"],"url":"https://github.com/WebReflection/flatted/releases/tag/v3.4.2"}],"affected":[{"vendor":"WebReflection","product":"flatted","versions":[{"version":"< 3.4.2","status":"affected"}]}],"providerMetadata":{"orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","shortName":"GitHub_M","dateUpdated":"2026-03-20T23:06:48.485Z"},"descriptions":[{"lang":"en","value":"flatted is a circular JSON parser. Prior to version 3.4.2, the parse() function in flatted can use attacker-controlled string values from the parsed JSON as direct array index keys, without validating that they are numeric. Since the internal input buffer is a JavaScript Array, accessing it with the key \"__proto__\" returns Array.prototype via the inherited getter. This object is then treated as a legitimate parsed value and assigned as a property of the output object, effectively leaking a live reference to Array.prototype to the consumer. Any code that subsequently writes to that property will pollute the global prototype. This issue has been patched in version 3.4.2."}],"source":{"advisory":"GHSA-rf6f-7fwh-wjgh","discovery":"UNKNOWN"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-03-24T17:35:34.197834Z","id":"CVE-2026-33228","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-03-24T17:57:22.866Z"}}]}}