CVE-2026-84994
Qwik: Crashing any Qwik Server via Resource thenable
CVE-2026-84994 is a high vulnerability (CVSS 8.7) in @builder.io Qwik, published October 13, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.52%, the 45th percentile. Fixed in @builder.io/qwik 1.20.0.
- Severity
- 8.7 HighCVSS 4.0, CVE List
- Exploit chance
- 0.52%EPSS, 45th percentile
- Exploitation
- None knownNot on CISA’s or ENISA’s lists
- Fixed in
1.20.0@builder.io/qwik +1 more
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
@builder.io/qwiknpm | before 1.20.0 | 1.20.0 |
@qwik.dev/corenpm | before 2.0.0-beta37 | 2.0.0-beta37 |
What each source reports
CVE List Score used
Qwik: Crashing any Qwik Server via Resource thenable
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.
- Record
CVE-2026-84994- CVSS 4.0
- 8.7 High
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 - Weakness
- CWE-248
- Updated
- 2026-11-02
EUVDEUVD-2026-99978
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.
- Record
EUVD-2026-99978- CVSS 4.0
- 8.7 High
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 - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-x586-xvc8-g7q6
Qwik: Crashing any Qwik Server via Resource thenable
Summary
A Qwik server in the default configuration can be crashed with one unauthenticated HTTP request. During qwik-json body parsing, ResourceSerializer.$fill$ does Promise.resolve(resource._resolved). If _resolved is a plain object whose .then is a QRL for an unregistered symbol, the async QRL rejects, the rejection is orphaned, and Node terminates the process via its default unhandled-rejection policy.
Impact
One unauthenticated request crashes the server. Looping keeps every replica dead as long as the attacker sends requests.
- Record
GHSA-x586-xvc8-g7q6- CVSS 4.0
- 8.7 High
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 - Weakness
- CWE-248
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2026-84994- CVSS 4.0
- 8.7 High
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - Weakness
- CWE-248
- Updated
- 2026-11-02
OSV
Qwik: Crashing any Qwik Server via Resource thenable
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.
- Record
CVE-2026-84994- CVSS 4.0
- 8.7 High
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 - Weakness
- CWE-248
- Updated
- 2026-11-02
OSVGHSA-x586-xvc8-g7q6
Qwik: Crashing any Qwik Server via Resource thenable
Summary
A Qwik server in the default configuration can be crashed with one unauthenticated HTTP request. During qwik-json body parsing, ResourceSerializer.$fill$ does Promise.resolve(resource._resolved). If _resolved is a plain object whose .then is a QRL for an unregistered symbol, the async QRL rejects, the rejection is orphaned, and Node terminates the process via its default unhandled-rejection policy.
Impact
One unauthenticated request crashes the server. Looping keeps every replica dead as long as the attacker sends requests.
- Record
GHSA-x586-xvc8-g7q6- CVSS 4.0
- 8.7 High
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 - Weakness
- CWE-248
- Updated
- 2026-11-02
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
References
github.com/QwikDev/qwik/security/advisories/GHSA-x586-xvc8-g7q6
nvd.nist.gov/vuln/detail/CVE-2026-84994