---
title: "CVE-2026-25142: SandboxJS Vulnerable to Prototype Pollution -> Sandbox Escape -> RCE"
url: https://erroneo.us/security/cve/CVE-2026-25142/
description: "CVE-2026-25142 (@nyariv/sandboxjs (npm)): SandboxJS is a JavaScript sandboxing library. Prior to 0.8.27, SanboxJS does not properly restrict lookupGetter…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-02-02
date_modified: 2026-02-18
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-25142"
kev: false
cvss: 10
epss: 0.01231
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-25142: SandboxJS Vulnerable to Prototype Pollution -> Sandbox Escape -> RCE

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 1.2% , percentile 69: FIRST’s model estimates a 1.2% chance of exploitation activity in the next 30 days, higher than 69% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes @nyariv/sandboxjs (npm) <= 0.8.26, fixed in 0.8.27 . Check your lockfile, including transitive dependencies.

## What it is

SandboxJS is a JavaScript sandboxing library. Prior to 0.8.27, SanboxJS does not properly restrict lookupGetter which can be used to obtain prototypes, which can be used for escaping the sandbox / remote code execution. This vulnerability is fixed in 0.8.27.

## Affected packages

- npm `@nyariv/sandboxjs` <= 0.8.26 → fixed: 0.8.27

## Affected products (CVE record)

- nyariv SandboxJS: < 0.8.27

## Severity

- GitHub_M CVSS 3.1: 10 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`
- GitHub CVSS 3.1: 10.0 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 1.23% probability of exploitation activity in the next 30 days; percentile 69.

## Sources

- [GitHub Advisory GHSA-9p4w-fq8m-2hp7](https://github.com/advisories/GHSA-9p4w-fq8m-2hp7)
- [CVE.org record CVE-2026-25142](https://www.cve.org/CVERecord?id=CVE-2026-25142)
- [NVD entry CVE-2026-25142](https://nvd.nist.gov/vuln/detail/CVE-2026-25142)
- [github.com](https://github.com/nyariv/SandboxJS/security/advisories/GHSA-9p4w-fq8m-2hp7)
- [github.com](https://github.com/nyariv/SandboxJS/commit/75c8009db32e6829b0ad92ca13bf458178442bd3)
- [github.com](https://github.com/nyariv/SandboxJS/blob/f212a38fb5a6d4bc2bc2e2466c0c011ce8d41072/src/executor.ts#L368-L398)

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Source page: https://erroneo.us/security/cve/CVE-2026-25142/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt