CVE-2026-27971: @builder.io/qwik Remote Code Execution Vulnerability

CRITICAL
Advisory Identifier: GHSA-p9x5-jp3h-96mm
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CWE-502
Published
Advisory Summary

CVE-2026-27971 is a CRITICAL remote code execution vulnerability (CWE-502: Deserialization of Untrusted Data) affecting @builder.io/qwik libraries in the npm ecosystem. The issue involves qwik vulnerable to unauthenticated rce via server$ deserialization. Remediation is available by upgrading affected packages to version 1.19.1.

CVE-2026-27971 at a Glance

CVE Identifier CVE-2026-27971
GHSA Identifier GHSA-p9x5-jp3h-96mm
Severity CRITICAL
CVSS v3.1 Base Score N/A
CWE Classification CWE-502: Deserialization of Untrusted Data
Affected Product @builder.io/qwik
Package Ecosystem npm
Published Date
Last Updated

How to Fix CVE-2026-27971

To remediate this vulnerability, upgrade all affected @builder.io/qwik 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 fixed: 1.19.1 
npm install @builder.io/qwik@1.19.1
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

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-27971, inspect your project dependencies using npm:

npm ls @builder.io/qwik

Analyze the terminal output to locate any version of @builder.io/qwik in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.19.1), your application is affected.

Note: The npm ls @builder.io/qwik 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-502: Deserialization of Untrusted Data, where the product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid. In @builder.io/qwik, 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 qwik <=1.19.0 is vulnerable to RCE due to an unsafe deserialization vulnerability in the `server$` RPC mechanism that allows any unauthenticated user to execute arbitrary code on the server with a single HTTP request. Affects any deployment where `require()` is available at runtime. ### Impact - Remote Code Execution

CVE-2026-27971 Affected @builder.io/qwik Versions

1 component(s)
Fixed Versions:
1.19.1
Product / Package Ecosystem Affected Versions Fixed Version
@builder.io/qwik
npm/@builder.io/qwik
npm
< 1.19.1
1.19.1

References

GitHub Advisory / Wiki ADVISORY
https://github.com/QwikDev/qwik/security/advisories/GHSA-p9x5-jp3h-96mm
NVD — CVE-2026-27971 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-27971
@builder.io/qwik Source Repository REPOSITORY
https://github.com/QwikDev/qwik
@builder.io/qwik Release RELEASE
https://github.com/QwikDev/qwik/releases/tag/%40builder.io%2Fqwik%401.19.1

Frequently Asked Questions

What is CVE-2026-27971?
CVE-2026-27971 is a security vulnerability in @builder.io/qwik involving Qwik vulnerable to Unauthenticated RCE via server$ Deserialization under CWE-502: Deserialization of Untrusted Data.
Which @builder.io/qwik versions are affected?
Affected versions include releases prior to 1.19.1 across affected packages: @builder.io/qwik.
What version fixes CVE-2026-27971?
Upgrading to 1.19.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is @builder.io/qwik affected?
Yes, @builder.io/qwik is affected in releases prior to 1.19.1. Upgrade your dependency to 1.19.1 or later.
What CWE is associated with CVE-2026-27971?
CVE-2026-27971 is classified under CWE-502: Deserialization of Untrusted Data (The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.).
How can I check npm dependencies for CVE-2026-27971?
Run the dependency tree command: 'npm ls @builder.io/qwik'. 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-p9x5-jp3h-96mm",
  "modified" : "2026-03-04T02:00:51Z",
  "published" : "2026-03-02T21:41:18Z",
  "aliases" : [ "CVE-2026-27971" ],
  "summary" : "Qwik vulnerable to Unauthenticated RCE via server$ Deserialization",
  "details" : "### Summary\nqwik <=1.19.0 is vulnerable to RCE due to an unsafe deserialization vulnerability in the `server$` RPC mechanism that allows any unauthenticated user to execute arbitrary code on the server with a single HTTP request. Affects any deployment where `require()` is available at runtime.\n\n### Impact\n- Remote Code Execution",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@builder.io/qwik"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.19.1"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 1.19.0"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/QwikDev/qwik/security/advisories/GHSA-p9x5-jp3h-96mm"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-27971"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/QwikDev/qwik"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/QwikDev/qwik/releases/tag/%40builder.io%2Fqwik%401.19.1"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-502" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-02T21:41:18Z",
    "nvd_published_at" : "2026-03-03T23:15:56Z"
  }
}