---
id: CVE-2026-43898
title: SandboxJS is a JavaScript sandboxing library
summary: >-
  SandboxJS is a JavaScript sandboxing library. Prior to 0.9.6, sandbox-defined
  functions expose Function.caller, allowing sandboxed code to recover the
  internal LispType.Call runtime callback. That callback can then be invoked
  with attack…
severity: critical
cvss: 10
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H'
cwe:
  - CWE-94
vendor: nyariv
product: sandboxjs
affected:
  - sandboxjs < 0.9.6
patched:
  - sandboxjs 0.9.6
published: '2026-05-28'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T20:10:00.190'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-43898'
references:
  - url: >-
      https://github.com/nyariv/SandboxJS/commit/826865251232611ec94078bab5a18ec875dad4a5
    label: security-advisories@github.com
  - url: >-
      https://github.com/nyariv/SandboxJS/security/advisories/GHSA-g8f2-4f4f-5jqw
    label: security-advisories@github.com
  - url: >-
      https://github.com/nyariv/SandboxJS/security/advisories/GHSA-g8f2-4f4f-5jqw
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
epss: 0.00632
epssPercentile: 0.49073
ingestedAt: '2026-10-14T20:53:12.341Z'
---

## Overview

SandboxJS is a JavaScript sandboxing library. Prior to 0.9.6, sandbox-defined functions expose Function.caller, allowing sandboxed code to recover the internal LispType.Call runtime callback. That callback can then be invoked with attacker-controlled fake context and obj values to extract blocked host statics, recover the real host Function constructor, and execute arbitrary host JavaScript. This vulnerability is fixed in 0.9.6.

## Affected

- `sandboxjs < 0.9.6`

## Remediation

Upgrade past the affected range:

- `sandboxjs 0.9.6`