CVE-2026-59952 (GCVE-0-2026-59952)
Vulnerability from cvelistv5 – Published: 2026-07-30 00:10 – Updated: 2026-07-30 00:10
VLAI
EPSS
VEX
Title
Valibot: record() issue paths can make flatten() throw for inherited Object property names
Summary
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.
Severity
CWE
- CWE-755 - Improper Handling of Exceptional Conditions
Assigner
References
4 references
| URL | Tags |
|---|---|
| https://github.com/open-circle/valibot/security/a… | x_refsource_CONFIRM |
| https://github.com/open-circle/valibot/pull/1522 | x_refsource_MISC |
| https://github.com/open-circle/valibot/commit/1bd… | x_refsource_MISC |
| https://github.com/open-circle/valibot/releases/t… | x_refsource_MISC |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| open-circle | valibot |
Affected:
< 1.4.2
|
{
"containers": {
"cna": {
"affected": [
{
"product": "valibot",
"vendor": "open-circle",
"versions": [
{
"status": "affected",
"version": "\u003c 1.4.2"
}
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}
],
"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\u0027s 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."
}
],
"metrics": [
{
"cvssV4_0": {
"attackComplexity": "LOW",
"attackRequirements": "NONE",
"attackVector": "NETWORK",
"baseScore": 6.9,
"baseSeverity": "MEDIUM",
"privilegesRequired": "NONE",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"userInteraction": "NONE",
"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",
"version": "4.0",
"vulnAvailabilityImpact": "LOW",
"vulnConfidentialityImpact": "NONE",
"vulnIntegrityImpact": "NONE"
}
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-755",
"description": "CWE-755: Improper Handling of Exceptional Conditions",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-07-30T00:10:32.598Z",
"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"shortName": "GitHub_M"
},
"references": [
{
"name": "https://github.com/open-circle/valibot/security/advisories/GHSA-5qjj-4xww-7phc",
"tags": [
"x_refsource_CONFIRM"
],
"url": "https://github.com/open-circle/valibot/security/advisories/GHSA-5qjj-4xww-7phc"
},
{
"name": "https://github.com/open-circle/valibot/pull/1522",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/open-circle/valibot/pull/1522"
},
{
"name": "https://github.com/open-circle/valibot/commit/1bd01c304657cd0809cc92694360b6cc60f700bf",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/open-circle/valibot/commit/1bd01c304657cd0809cc92694360b6cc60f700bf"
},
{
"name": "https://github.com/open-circle/valibot/releases/tag/v1.4.2",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/open-circle/valibot/releases/tag/v1.4.2"
}
],
"source": {
"advisory": "GHSA-5qjj-4xww-7phc",
"discovery": "UNKNOWN"
},
"title": "Valibot: record() issue paths can make flatten() throw for inherited Object property names"
}
},
"cveMetadata": {
"assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"assignerShortName": "GitHub_M",
"cveId": "CVE-2026-59952",
"datePublished": "2026-07-30T00:10:32.598Z",
"dateReserved": "2026-07-07T18:49:15.607Z",
"dateUpdated": "2026-07-30T00:10:32.598Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
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}
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
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