Bug 2487740 (CVE-2026-46625) - CVE-2026-46625 js-cookie: JavaScript Cookie: Cookie attribute manipulation via prototype pollution
Summary: CVE-2026-46625 js-cookie: JavaScript Cookie: Cookie attribute manipulation vi...
Keywords:
Status: NEW
Alias: CVE-2026-46625
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-06-10 22:01 UTC by OSIDB Bzimport
Modified: 2026-06-29 17:35 UTC (History)
86 users (show)

Fixed In Version:
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Description OSIDB Bzimport 2026-06-10 22:01:40 UTC
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.


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