QwikDev Qwik ResourceSerializer ResourceSerializer.$fill$ resource deserialization

Summaryinfo

A vulnerability was found in QwikDev Qwik. It has been classified as critical. This issue affects the function ResourceSerializer.$fill$ of the component ResourceSerializer. This manipulation of the argument resource causes deserialization. This vulnerability is tracked as CVE-2026-84994. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability was found in QwikDev Qwik (unknown version). It has been declared as critical. Affected by this vulnerability is the function ResourceSerializer.$fill$ of the component ResourceSerializer. The manipulation of the argument resource with an unknown input leads to a deserialization vulnerability. The CWE definition for the vulnerability is CWE-502. The product deserializes untrusted data without sufficiently verifying that the resulting data will be valid. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

Qwik is a performance-focused JavaScript framework. Prior to @builder.io/qwik 1.20.0 and @qwik.dev/core 2.0.0-beta.37, default server-side qwik-json deserialization causes ResourceSerializer.$fill$ to pass resource._resolved to Promise.resolve without first rejecting attacker-controlled thenables. An unauthenticated request can provide a plain object whose then property is a QRL for an unregistered symbol, causing an orphaned asynchronous rejection that terminates Node.js under its default unhandled-rejection policy. A single request can crash a server, and repeated requests can keep replicas unavailable. This issue is fixed in @builder.io/qwik 1.20.0 and @qwik.dev/core 2.0.0-beta.37.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-84994 since 09/02/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 10/14/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Vendor

• QwikDev

Name

• Qwik

Website

• Product: https://github.com/QwikDev/qwik/

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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