---
id: CVE-2026-25521
title: >-
  Locutus brings stdlibs of other programming languages to JavaScript for
  educational purposes
summary: >-
  Locutus brings stdlibs of other programming languages to JavaScript for
  educational purposes. In versions from 2.0.12 to before 2.0.39, a prototype
  pollution vulnerability exists in locutus. Despite a previous fix that
  attempted to mitig…
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H'
cwe:
  - CWE-1321
  - CWE-915
vendor: locutus
product: locutus
affected:
  - 'locutus >= 2.0.12, < 2.0.39'
patched:
  - locutus 2.0.39
published: '2026-02-04'
updated: '2026-06-27'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-25521'
references:
  - url: >-
      https://github.com/locutusjs/locutus/commit/042af9ca7fde2ff599120783e720a17f335bb01c
    label: security-advisories@github.com
  - url: >-
      https://github.com/locutusjs/locutus/security/advisories/GHSA-rxrv-835q-v5mh
    label: security-advisories@github.com
  - url: 'https://access.redhat.com/security/cve/CVE-2026-25521'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2436950'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-25521.json
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
tags:
  - nvd
epss: 0.00444
epssPercentile: 0.35997
ingestedAt: '2026-06-29T13:24:34.638Z'
---

## Overview

Locutus brings stdlibs of other programming languages to JavaScript for educational purposes. In versions from 2.0.12 to before 2.0.39, a prototype pollution vulnerability exists in locutus. Despite a previous fix that attempted to mitigate prototype pollution by checking whether user input contained a forbidden key, it is still possible to pollute Object.prototype via a crafted input using String.prototype. This issue has been patched in version 2.0.39.

## Affected

- `locutus >= 2.0.12, < 2.0.39`

## Remediation

Upgrade past the affected range:

- `locutus 2.0.39`