CVE-2026-84994

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.

CVSS 4.0

8.7CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

EPSS

0.5% chance of exploitation in the next 30 days; higher than 44% of CVEs (scores of 2026-10-25)

CWE

CWE-248

Published

2026-10-13

Modified

2026-10-14

Record from

the NVD, synced 2026-10-19

Packages (OSV)

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

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