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

> An unauthenticated attacker can crash a Qwik server by sending a crafted request that triggers an unhandled promise rejection, causing a denial of service.

- **Severity:** High 8.7 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 13 Oct 2026
- **Updated:** 14 Oct 2026
- **Also known as:** GHSA-x586-xvc8-g7q6

## What is CVE-2026-84994?

CVE-2026-84994 is a high-severity denial of service vulnerability in @builder.io qwik, published on 13 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### 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.

Weakness: CWE-248 (Uncaught Exception)

## Which versions are affected by CVE-2026-84994?

4 open source packages ship an affected version, including @builder.io/qwik and @qwik.dev/core.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `@builder.io/qwik` | npm | All versions | 1.20.0 |
| `@builder.io/qwik` | npm | All versions | 1.20.0 |
| `@qwik.dev/core` | npm | All versions | 2.0.0-beta37 |
| `@qwik.dev/core` | npm | All versions | 2.0.0-beta37 |

## How do I fix CVE-2026-84994?

Upgrade @builder.io/qwik to 1.20.0 or later.

## Is CVE-2026-84994 being exploited?

There is no known exploitation of CVE-2026-84994 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-84994 and fix it if it is affected.

What it is: CVE-2026-84994 is a high-severity denial of service vulnerability in @builder.io qwik, published on 13 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-84994 in the wild and no public exploit code.

Affected packages and fixed versions:
- @builder.io/qwik (npm): affected all versions; fixed in 1.20.0
- @builder.io/qwik (npm): affected all versions; fixed in 1.20.0
- @qwik.dev/core (npm): affected all versions; fixed in 2.0.0-beta37
- @qwik.dev/core (npm): affected all versions; fixed in 2.0.0-beta37

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-84994/ (Markdown: https://insights.sbomify.com/CVE-2026-84994/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-84994
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-84994
- OSV: https://osv.dev/vulnerability/CVE-2026-84994

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-84994/
Summaries are generated and may contain mistakes; the official description above is the record.