Qwik has a potential mXSS vulnerability due to improper HTML escaping
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 software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | @builder.io/qwik | < 1.7.3 | 1.7.3 |
References
- https://github.com/QwikDev/qwik/security/advisories/GHSA-2rwj-7xq8-4gx4
- https://nvd.nist.gov/vuln/detail/CVE-2024-41677
- https://github.com/QwikDev/qwik/commit/7e742eb3a1001542d795776c0317d47df8b9d64e
- https://github.com/QwikDev/qwik
- https://github.com/QwikDev/qwik/blob/v1.5.5/packages/qwik/src/core/render/ssr/render-ssr.ts#L1182-L1208
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L- Weakness (CWE)
CWE-79- Platform
- npm
- Package
@builder.io/qwik- Disclosed
- 06.08.2024
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-2rwj-7xq8-4gx4 - CC BY 4.0
Vulnerability history: @builder.io/qwik
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 5
- First → latest
- 01.2023 10.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 2
- High 1
- Medium 2
Disclosures per year
- 2023: 2
- 2024: 1
- 2025: 0
- 2026: 2
-
Qwik has a potential mXSS vulnerability due to improper HTML escaping this entry
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