CVE-2026-25150: @builder.io/qwik city Prototype Pollution Vulnerability

CRITICAL
Advisory Identifier: GHSA-xqg6-98cw-gxhq
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CVSS 9.3
CWE-1321
Published
Advisory Summary

CVE-2026-25150 is a CRITICAL (CVSS 9.3) prototype pollution vulnerability (CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')) affecting @builder.io/qwik city libraries in the npm ecosystem. The issue involves prototype pollution via formdata processing in qwik city. Remediation is available by upgrading affected packages to version 1.19.0.

CVE-2026-25150 at a Glance

CVE Identifier CVE-2026-25150
GHSA Identifier GHSA-xqg6-98cw-gxhq
Severity CRITICAL
CVSS v3.1 Base Score 9.3
CWE Classification CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Affected Product @builder.io/qwik city
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 9.3

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:L).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Changed (S:C)
Confidentiality None (C:N)
Integrity High (I:H)
Availability Low (A:L)

How to Fix CVE-2026-25150

To remediate this vulnerability, upgrade all affected @builder.io/qwik city dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

@builder.io/qwik-city fixed: 1.19.0 
npm install @builder.io/qwik-city@1.19.0
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls @builder.io/qwik-city

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-25150, inspect your project dependencies using npm:

npm ls @builder.io/qwik-city

Analyze the terminal output to locate any version of @builder.io/qwik city in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.19.0), your application is affected.

Note: The npm ls @builder.io/qwik-city command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution'), where the product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype. In @builder.io/qwik city, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Summary 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. ### Impact An unauthenticated attacker can supply specially crafted form field names that cause formToObj() to write dangerous keys (for example __proto__, constructor, prototype) into parsed objects. This results in Prototype Pollution of the server process and can cause privilege escalation, auth bypass, denial-of-service, or other global application integrity failures depending on how objects are used.

CVE-2026-25150 Affected @builder.io/qwik city Versions

1 component(s)
Fixed Versions:
1.19.0
Product / Package Ecosystem Affected Versions Fixed Version
@builder.io/qwik-city
npm/@builder.io/qwik-city
npm
< 1.19.0
1.19.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/QwikDev/qwik/security/advisories/GHSA-xqg6-98cw-gxhq
NVD — CVE-2026-25150 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-25150
Security Fix Commit FIX COMMIT
https://github.com/QwikDev/qwik/commit/5f65bae2bc33e6ca0c21e4cfcf9eae05077716f7
@builder.io/qwik city Source Repository REPOSITORY
https://github.com/QwikDev/qwik

Frequently Asked Questions

What is CVE-2026-25150?
CVE-2026-25150 is a security vulnerability in @builder.io/qwik city involving Prototype Pollution via FormData Processing in Qwik City under CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution').
Which @builder.io/qwik city versions are affected?
Affected versions include releases prior to 1.19.0 across affected packages: @builder.io/qwik-city.
What version fixes CVE-2026-25150?
Upgrading to 1.19.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is @builder.io/qwik-city affected?
Yes, @builder.io/qwik-city is affected in releases prior to 1.19.0. Upgrade your dependency to 1.19.0 or later.
What is the CVSS score of CVE-2026-25150?
CVE-2026-25150 has a CVSS v3.1 base score of 9.3 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:L.
What CWE is associated with CVE-2026-25150?
CVE-2026-25150 is classified under CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') (The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.).
How can I check npm dependencies for CVE-2026-25150?
Run the dependency tree command: 'npm ls @builder.io/qwik-city'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-xqg6-98cw-gxhq",
  "modified" : "2026-02-04T17:45:43Z",
  "published" : "2026-02-03T20:49:22Z",
  "aliases" : [ "CVE-2026-25150" ],
  "summary" : "Prototype Pollution via FormData Processing in Qwik City",
  "details" : "### Summary\n\nA 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.\n\n### Impact\nAn unauthenticated attacker can supply specially crafted form field names that cause formToObj() to write dangerous keys (for example __proto__, constructor, prototype) into parsed objects. This results in Prototype Pollution of the server process and can cause privilege escalation, auth bypass, denial-of-service, or other global application integrity failures depending on how objects are used.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@builder.io/qwik-city"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.19.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/QwikDev/qwik/security/advisories/GHSA-xqg6-98cw-gxhq"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-25150"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/QwikDev/qwik/commit/5f65bae2bc33e6ca0c21e4cfcf9eae05077716f7"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/QwikDev/qwik"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1321" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-02-03T20:49:22Z",
    "nvd_published_at" : "2026-02-03T22:16:30Z"
  }
}