Prototype Pollution in Qwik-City Middleware Enables Privilege Escalation

Executive Summary

This vulnerability exists in the Qwik JavaScript framework prior to version 1.19.0, specifically in the formToObj() function within the @builder.io/qwik-city middleware. The function converts form field names that use dot notation (like user.name) into nested objects but does not properly sanitize dangerous property names such as __proto__, constructor, and prototype.

Because of this lack of sanitization, an unauthenticated attacker can send specially crafted HTTP POST requests that manipulate these dangerous property names, leading to prototype pollution. Prototype pollution allows the attacker to modify the Object.prototype, which can affect all objects in the application.

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Detection Guidance

I don't know

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Impact Analysis

The prototype pollution vulnerability can have serious impacts including privilege escalation, authentication bypass, and denial of service.

• Privilege escalation: Attackers may gain higher-level permissions than intended.
• Authentication bypass: Attackers might bypass authentication mechanisms.
• Denial of service: The application could be made unavailable or unstable.

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Compliance Impact

I don't know

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Mitigation Strategies

To mitigate this vulnerability, you should upgrade the @builder.io/qwik-city middleware to version 1.19.0 or later, where the prototype pollution issue in the formToObj() function has been patched.

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