What’s Vulnerable › Vulnerabilities

CVE-2026-84994: Qwik: Crashing any Qwik Server via Resource thenable

• Severity: high (CVSS 8.7 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-13 · updated 2026-10-14
• Weakness: CWE-248

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 products

• @builder.io qwik: before 1.20.0
• QwikDev qwik: before 2.0.0-beta37

References

• https://github.com/QwikDev/qwik/commit/c1e7444402f9592b5cf9096e10bf303ab4640511
• https://github.com/QwikDev/qwik/pull/8655
• https://github.com/QwikDev/qwik/releases/tag/@builder.io/qwik@1.20.0
• https://github.com/QwikDev/qwik/security/advisories/GHSA-x586-xvc8-g7q6

Get alerted when CVE-2026-84994 or the next vulnerability affects your stack