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.
History

Thu, 05 Feb 2026 15:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Thu, 05 Feb 2026 12:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-915
References
Metrics threat_severity

None

cvssV3_1

{'score': 9.3, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H'}

threat_severity

Critical


Thu, 05 Feb 2026 11:45:00 +0000

Type Values Removed Values Added
First Time appeared Locutus
Locutus locutus
Vendors & Products Locutus
Locutus locutus

Wed, 04 Feb 2026 21:30:00 +0000

Type Values Removed Values Added
Description 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.
Title Locutus is vulnerable to Prototype Pollution
Weaknesses CWE-1321
References
Metrics cvssV4_0

{'score': 9.4, 'vector': 'CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-02-05T14:31:43.203Z

Reserved: 2026-02-02T18:21:42.487Z

Link: CVE-2026-25521

cve-icon Vulnrichment

Updated: 2026-02-05T14:23:07.923Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-02-04T22:15:59.203

Modified: 2026-02-05T14:57:20.563

Link: CVE-2026-25521

cve-icon Redhat

Severity : Critical

Publid Date: 2026-02-04T21:20:32Z

Links: CVE-2026-25521 - Bugzilla