{"id":"CVE-2026-59952","sourceIdentifier":"security-advisories@github.com","published":"2026-07-30T01:17:06.840","lastModified":"2026-10-23T22:10:00.160","vulnStatus":"Deferred","cveTags":[],"descriptions":[{"lang":"en","value":"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."},{"lang":"es","value":"Valibot ayuda a validar datos usando un esquema. Las versiones anteriores a la 1.4.2 pueden lanzar un TypeError dentro de su ayudante flatten() cuando los problemas de validación contienen claves de objeto controladas por el atacante, como toString, valueOf o hasOwnProperty. El problema es alcanzable a través de la validación normal de record(). record() filtra intencionadamente __proto__, prototype y constructor, pero aún acepta otras claves propias que colisionan con propiedades heredadas de Object.prototype. Si el esquema de clave de registro o el esquema de valor rechaza dicha entrada, Valibot crea una ruta de problema que contiene esa clave. Pasar los problemas resultantes al ayudante flatten() documentado de Valibot hace que flatErrors.nested[dotPath] se resuelva al método heredado en lugar de una matriz de errores propia, y el ayudante llama a .push(...) en esa función. Esto no es un problema de contaminación global de prototipos. El impacto es disponibilidad/manejo de errores: las aplicaciones que validan objetos controlados por el usuario con record() y aplanan los errores de validación para las respuestas de la API pueden bloquear la ruta de la solicitud con un TypeError en lugar de devolver errores de validación estructurados. Este problema ha sido corregido en la versión 1.4.2."}],"affected":[{"source":"security-advisories@github.com","affectedData":[{"vendor":"open-circle","product":"valibot","versions":[{"version":"< 1.4.2","status":"affected"}]}]}],"metrics":{"cvssMetricV40":[{"source":"security-advisories@github.com","type":"Secondary","cvssData":{"version":"4.0","vectorString":"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/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":6.9,"baseSeverity":"MEDIUM","attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnAvailabilityImpact":"LOW","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"}}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-07-30T14:41:28.900290Z","id":"CVE-2026-59952","options":[{"exploitation":"poc"},{"automatable":"yes"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"weaknesses":[{"source":"security-advisories@github.com","type":"Secondary","description":[{"lang":"en","value":"CWE-755"}]}],"references":[{"url":"https://github.com/open-circle/valibot/commit/1bd01c304657cd0809cc92694360b6cc60f700bf","source":"security-advisories@github.com"},{"url":"https://github.com/open-circle/valibot/pull/1522","source":"security-advisories@github.com"},{"url":"https://github.com/open-circle/valibot/releases/tag/v1.4.2","source":"security-advisories@github.com"},{"url":"https://github.com/open-circle/valibot/security/advisories/GHSA-5qjj-4xww-7phc","source":"security-advisories@github.com"},{"url":"https://github.com/open-circle/valibot/security/advisories/GHSA-5qjj-4xww-7phc","source":"134c704f-9b21-4f2e-91b3-4a467353bcc0"}]}