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[ CVE-2026-84994 · Published 13 Oct 2026 ]

Qwik: Crashing any Qwik Server via Resource thenable

CVSS 8.7 EPSS <1%Fix available

[ Description ]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.

[ Fixes ]Fixes and patches

  • @builder.io/qwik 1.20.0Fixed version · GitHub Advisories · npm package @builder.io/qwik: upgrade to 1.20.0 or later (affected < 1.20.0)
  • @qwik.dev/core 2.0.0-beta37Fixed version · GitHub Advisories · npm package @qwik.dev/core: upgrade to 2.0.0-beta37 or later (affected < 2.0.0-beta37)

[ Packages ]Affected open-source packages

[ References ]References