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The vulnerability exists in the internal `mergeDeep` utility function used by Vuetify’s Preset configuration feature to merge user-provided options with default settings. This function does not properly validate or sanitize keys during the merge operation. An attacker can exploit this by passing a specially crafted malicious preset object containing keys like __proto__, constructor, or prototype. When `mergeDeep` processes this object, it inadvertently assigns properties to the fundamental Object.prototype. This pollutes the prototype chain, causing every new JavaScript object created in the application to inherit these malicious properties. This can fundamentally alter the application’s behavior, leading to security breaches. In Server-Side Rendering (SSR) scenarios, this pollution can affect the entire server process.
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Platform: Vuetify
Version: >=2.2.0-beta.2 <3.0.0-alpha.10
Vulnerability: Prototype Pollution
Severity: High (CVSS 8.6)
Date: 2025-12-11
Prediction: No upstream patch
What Undercode Say:
Check if an object is initially clean
const cleanObj = {};
console.log('cleanObj.polluted:', cleanObj.polluted); // undefined
// Malicious preset payload to pollute the prototype
const maliciousOption = JSON.parse('{"preset": {"<strong>proto</strong>": {"polluted": true}}}');
// Initialize Vuetify with the malicious option
new Vue({
el: 'app',
vuetify: new Vuetify(maliciousOption),
});
// Confirm pollution: all objects now have the 'polluted' property
console.log('cleanObj.polluted:', cleanObj.polluted); // true
console.log('({}).polluted:', ({}).polluted); // true
How Exploit:
Attackers craft a configuration object containing a `__proto__` property and deliver it to the `mergeDeep` function. This is achieved by passing the malicious object as a preset during Vuetify initialization (new Vuetify(maliciousOption)). The payload can be delivered via user-controlled input that ends up in the preset configuration, or through a server-side request in SSR contexts.
Protection from this CVE:
- Migrate or Patch: Migrate to Vuetify 3 or apply a patched version (like Vuetify NES v2.7.4) from a commercial support provider.
- Input Sanitization: Validate and sanitize all objects before passing them to Vuetify. Recursively filter out dangerous keys like
__proto__,constructor, andprototype. - Use Safe Objects: For temporary objects handling untrusted data, use `Object.create(null)` to create a prototype-less object.
- Freeze Prototypes: In high-security environments, consider using `Object.freeze(Object.prototype)` to prevent prototype pollution at runtime.
Impact:
Security Bypass: Pollution can alter application logic, potentially leading to privilege escalation or unauthorized data access.
Denial of Service: Injected properties can cause application crashes or resource exhaustion.
Server-Side Compromise: For SSR applications, the vulnerability can pollute the Node.js server process, causing widespread instability or data corruption.
Remote Code Execution: In specific conditions, prototype pollution can be a precursor to arbitrary code execution.
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Sources:
Reported By: github.com
Extra Source Hub:
Undercode
