CVE-2026-25521

CRITICAL CVSS 4.0: 9.4 EPSS 0.26%
Updated Feb 05, 2026
Locutus
Parameter Value
CVSS 9.4 (CRITICAL)
Affected Versions before 2.0.39
Fixed In 2.0.39
Type CWE-1321 (Prototype Pollution)
Vendor Locutus
Public PoC No

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.

Attack Parameters

Attack Vector
Local
Requires local access
Attack Complexity
Low
Easy to exploit
Attack Requirements
None
No additional conditions
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed

Impact Assessment

Confidentiality
High
Complete data leak
Integrity
High
Complete data modification
Availability
High
Complete denial of service

CVSS Vector v4.0

Weakness Type (CWE)