Vulnerability Details CVE-2026-46625
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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.008
EPSS Ranking 54.4%
CVSS Severity
CVSS v3 Score 7.5
Products affected by CVE-2026-46625
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cpe:2.3:a:js-cookie:javascript_cookie:*
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cpe:2.3:a:redhat:3scale_api_management:2.0
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cpe:2.3:a:redhat:ansible_automation_platform:2.0
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cpe:2.3:a:redhat:openshift_ai:-
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cpe:2.3:a:redhat:openshift_lightspeed:-
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cpe:2.3:o:redhat:enterprise_linux:10.0
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cpe:2.3:o:redhat:enterprise_linux:8.0
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cpe:2.3:o:redhat:enterprise_linux:9.0