GHSA-2rwj-7xq8-4gx4
MEDIUMQwik has a potential mXSS vulnerability due to improper HTML escaping
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
@builder.io/qwikReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.
Description
Summary
A potential mXSS vulnerability exists in Qwik for versions up to 1.6.0.
Details
Qwik improperly escapes HTML on server-side rendering. It converts strings according to the following rules:
- If the string is an attribute value:
"->"&->&- Other characters -> No conversion
- Otherwise:
<-><>->>&->&- Other characters -> No conversion
It sometimes causes the situation that the final DOM tree rendered on browsers is different from what Qwik expects on server-side rendering. This may be leveraged to perform XSS attacks, and a type of the XSS is known as mXSS (mutation XSS).
PoC
A vulnerable component:
import { component$ } from "@builder.io/qwik";
import { useLocation } from "@builder.io/qwik-city";
export default component$(() => {
// user input
const { url } = useLocation();
const href = url.searchParams.get("href") ?? "https://example.com";
return (
<div>
<noscript>
<a href={href}>test</a>
</noscript>
</div>
);
});
If a user accesses the following URL,
http://localhost:4173/?href=</noscript><script>alert(123)</script>
then, alert(123) will be executed.
Impact
XSS
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @builder.io/qwik | all versions | 1.7.3 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @builder.io/qwik. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update @builder.io/qwik to 1.7.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-2rwj-7xq8-4gx4 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-2rwj-7xq8-4gx4 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-2rwj-7xq8-4gx4. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-2rwj-7xq8-4gx4 in your dependencies?
O3 detects GHSA-2rwj-7xq8-4gx4 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.