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1 vulnerability by js-cookie
CVE-2026-46625 (GCVE-0-2026-46625)
Vulnerability from cvelistv5 – Published: 2026-06-10 21:18 – Updated: 2026-06-11 16:14
VLAI
Title
JavaScript Cookie: Per-instance prototype hijack in assign() enables cookie-attribute injection
Summary
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.
Severity
7.5 (High)
SSVC
Exploitation: poc
Automatable: yes
Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
- CWE-1321 - Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://github.com/js-cookie/js-cookie/security/a… | x_refsource_CONFIRM |
| https://github.com/js-cookie/js-cookie/commit/eb3… | x_refsource_MISC |
| https://github.com/js-cookie/js-cookie/releases/t… | x_refsource_MISC |
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