CVE-2026-84994 · GHSA-x586-xvc8-g7q6

Qwik: Crashing any Qwik Server via Resource thenable

Risk score: 71/100
CVSS: 8.7 v4.0
Exploit chance (30 days): 0.5%
Published: 13 Oct 2026

Open in the live forecast Today's forecast

What to know

What it 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 r…
Affected: @builder.io/qwik (npm) < 1.20.0; @qwik.dev/core (npm) < 2.0.0-beta37
Fix: Upgrade @builder.io/qwik to 1.20.0; @qwik.dev/core to 2.0.0-beta37 or later.
Exploitation: No known exploitation

Why it is Amber

CVSS 8.7 high
Remotely exploitable without logging in
On your watchlist: npm

Affected packages

Package	Ecosystem	Vulnerable	Fixed in
@builder.io/qwik	npm	< 1.20.0	1.20.0
@qwik.dev/core	npm	< 2.0.0-beta37	2.0.0-beta37

References

Original 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.

Last activity 13 Oct 2026. Patch Forecast updates every hour.