Vulnerability · Published Oct 13, 2026 · Assigned by GitHub_M
CVE-2026-84994Qwik: Crashing any Qwik Server via Resource thenable
High 8.7
In plain English
A high-severity security flaw in qwik from @builder.io. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 45% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | @builder.io/qwik | 1.20.0 | GHSA-x586-xvc8-g7q6 |
| npm | @qwik.dev/core | 2.0.0-beta37 | GHSA-x586-xvc8-g7q6 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| QwikDev | qwik | < 2.0.0-beta37 |
| @builder.io | qwik | < 1.20.0 |
Weakness: CWE-248 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
References
- https://github.com/QwikDev/qwik/security/advisories/GHSA-x586-xvc8-g7q6 x_refsource_CONFIRM
- https://github.com/QwikDev/qwik/pull/8655 x_refsource_MISC
- https://github.com/QwikDev/qwik/commit/c1e7444402f9592b5cf9096e10bf303ab4640511 x_refsource_MISC
- https://github.com/QwikDev/qwik/releases/tag/@builder.io/qwik@1.20.0 x_refsource_MISC