Improper Handling of Exceptional Conditions Affecting valibot package, versions <1.4.2
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-JS-VALIBOT-18313048
- published26 Jul 2026
- disclosed24 Jul 2026
- creditFaze-up
Introduced: 24 Jul 2026
NewCVE-2026-59952 (opens in a new tab)How to fix?
Upgrade valibot to version 1.4.2 or higher.
Overview
valibot is a The modular and type safe schema library for validating structural data
Affected versions of this package are vulnerable to Improper Handling of Exceptional Conditions in the flatten process. An attacker can cause the application to throw a TypeError and disrupt normal error handling by submitting specially crafted JSON objects containing keys that collide with inherited Object.prototype property names, such as toString, valueOf, or hasOwnProperty, which are then processed by the validation and error-flattening logic.