JavaScript Cookie is a JavaScript API for handling cookies, client-side. Prior to version 3.0.7, js-cookie's internal assign() helper copies properties with for...in + plain assignment. When the source object is produced by JSON.parse, the JSON object's "__proto__" member is an own enumerable property, so the for…in enumerates it and the target[key] = source[key] write triggers the Object.prototype.__proto__ setter on the fresh target ({}). The result is a per-instance prototype hijack: Object.prototype itself is untouched, but the merged attributes object now inherits attacker-controlled keys. Because the consuming set() function then enumerates the merged object with another for...in, every key the attacker placed on the polluted prototype lands in the resulting Set-Cookie string as an attribute pair. The attacker can set domain=, secure=, samesite=, expires=, and path= on cookies whose attributes the developer thought were locked down. This issue has been patched in version 3.0.7.
References
Configurations
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History
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Information
Published : 2026-06-10 22:16
Updated : 2026-09-09 13:20
NVD link : CVE-2026-46625
Mitre link : CVE-2026-46625
CVE.ORG link : CVE-2026-46625
JSON object : View
Products Affected
redhat
- enterprise_linux
- openshift_ai
- ansible_automation_platform
- openshift_lightspeed
- 3scale_api_management
js-cookie
- javascript_cookie
