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Vulnerability · Published Feb 4, 2026 · Assigned by GitHub_M

CVE-2026-25521Locutus is vulnerable to Prototype Pollution

Critical 9.3

In plain English

A critical-severity prototype pollution in locutus from locutusjs. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 24% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)9.3Critical
Exploit odds (30 days)0.3%top 75.5% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
npmlocutus2.0.39GHSA-rxrv-835q-v5mh

Affected products (as reported)

VendorProductVersions
locutusjs locutus >= 2.0.12, < 2.0.39

Weakness: CWE-1321, CWE-915 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

References