{"id":"CVE-2026-33228","revision":"e60b953536fd451a8aefaf5a743b4c23","records":[{"revision":"e60b953536fd451a8aefaf5a743b4c23","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-33228","aliases":[],"title":"flatted: Prototype Pollution via parse()","description":"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.","state":0,"publishedAt":"2026-03-20T23:06:48.485+00:00","modifiedAt":"2026-09-07T12:05:12.907+00:00","affected":[{"ecosystem":"Vendor product","name":"flatted","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"WebReflection\",\n                    \"product\": \"flatted\",\n                    \"versions\": [\n                        {\n                            \"version\": \"< 3.4.2\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 4.0","vector":"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","score":8.9,"severity":"HIGH"}],"references":["https://github.com/WebReflection/flatted/security/advisories/GHSA-rf6f-7fwh-wjgh","https://github.com/WebReflection/flatted/commit/885ddcc33cf9657caf38c57c7be45ae1c5272802","https://github.com/WebReflection/flatted/releases/tag/v3.4.2"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-33228","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-33228","identifiers":["CVE-2026-33228"]},"retained":false,"historicalAffected":[]}],"coverage":[]}