{"cve":"CVE-2026-59952","nvd":{"published":"2026-07-30T01:17:06.840","modified":"2026-10-23T22:10:00.160","status":"Deferred","description":"Valibot helps validate data using a schema. Versions prior to 1.4.2 can throw a TypeError inside its flatten() helper when validation issues contain attacker-controlled object keys such as toString, valueOf, or hasOwnProperty. The issue is reachable through normal record() validation. record() intentionally filters __proto__, prototype, and constructor, but it still accepts other own keys that collide with inherited Object.prototype properties. If the record key schema or value schema rejects such an entry, Valibot creates an issue path containing that key. Passing the resulting issues to Valibot's documented flatten() helper causes flatErrors.nested[dotPath] to resolve to the inherited method instead of an own error array, and the helper calls .push(...) on that function. This is not a global prototype pollution issue. The impact is availability/error handling: applications that validate user-controlled objects with record() and flatten validation errors for API responses can crash the request path with a TypeError instead of returning structured validation errors. This issue has been fixed in version 1.4.2.","cvss_v4":{"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","score":6.9},"cvss_v3":null,"cwes":["CWE-755"],"references":["https://github.com/open-circle/valibot/commit/1bd01c304657cd0809cc92694360b6cc60f700bf","https://github.com/open-circle/valibot/pull/1522","https://github.com/open-circle/valibot/releases/tag/v1.4.2","https://github.com/open-circle/valibot/security/advisories/GHSA-5qjj-4xww-7phc","https://github.com/open-circle/valibot/security/advisories/GHSA-5qjj-4xww-7phc"],"products":[],"source":"nvd","synced_at":"2026-10-24T16:53:34.184483516+00:00"},"epss":{"cve":"CVE-2026-59952","score":0.00383,"percentile":0.32061,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-5qjj-4xww-7phc","url":"https://osv.dev/vulnerability/GHSA-5qjj-4xww-7phc","summary":"Valibot: record() issue paths can make flatten() throw for inherited Object property names","modified":"2026-07-24T16:33:10.281535Z","packages":[{"ecosystem":"npm","name":"valibot","purl":"pkg:npm/valibot","ranges":["<1.4.2"],"fixed":["1.4.2"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}