---
title: "CVE-2026-25150: Prototype Pollution via FormData Processing in Qwik City"
url: https://erroneo.us/security/cve/CVE-2026-25150/
description: "CVE-2026-25150 (@builder.io/qwik-city (npm)): Qwik is a performance focused javascript framework. Prior to version 1.19.0, a prototype pollution…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-02-03
date_modified: 2026-02-04
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-25150"
kev: false
cvss: 9.3
epss: 0.00719
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-25150: Prototype Pollution via FormData Processing in Qwik City

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.7% , percentile 53: FIRST’s model estimates a 0.7% chance of exploitation activity in the next 30 days, higher than 53% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes @builder.io/qwik-city (npm) < 1.19.0, fixed in 1.19.0 . Check your lockfile, including transitive dependencies.

## What it is

Qwik is a performance focused javascript framework. Prior to version 1.19.0, a prototype pollution vulnerability exists in the formToObj() function within @builder.io/qwik-city middleware. The function processes form field names with dot notation (e.g., user.name) to create nested objects, but fails to sanitize dangerous property names like proto, constructor, and prototype. This allows unauthenticated attackers to pollute Object.prototype by sending crafted HTTP POST requests, potentially leading to privilege escalation, authentication bypass, or denial of service. This issue has been patched in version 1.19.0.

## Affected packages

- npm `@builder.io/qwik-city` < 1.19.0 → fixed: 1.19.0

## Affected products (CVE record)

- QwikDev qwik: < 1.19.0

## Severity

- GitHub_M CVSS 3.1: 9.3 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:L`
- GitHub CVSS 3.1: 9.3 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:L`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none , automatable yes , technical impact partial .
- FIRST EPSS (model of 2026-10-21): 0.72% probability of exploitation activity in the next 30 days; percentile 53.

## Sources

- [GitHub Advisory GHSA-xqg6-98cw-gxhq](https://github.com/advisories/GHSA-xqg6-98cw-gxhq)
- [CVE.org record CVE-2026-25150](https://www.cve.org/CVERecord?id=CVE-2026-25150)
- [NVD entry CVE-2026-25150](https://nvd.nist.gov/vuln/detail/CVE-2026-25150)
- [github.com](https://github.com/QwikDev/qwik/security/advisories/GHSA-xqg6-98cw-gxhq)
- [github.com](https://github.com/QwikDev/qwik/commit/5f65bae2bc33e6ca0c21e4cfcf9eae05077716f7)

---
Source page: https://erroneo.us/security/cve/CVE-2026-25150/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt