CVE-2026-25521

critical

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.

References

https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-25521.json

https://github.com/locutusjs/locutus/security/advisories/GHSA-rxrv-835q-v5mh

https://github.com/locutusjs/locutus/commit/042af9ca7fde2ff599120783e720a17f335bb01c

https://bugzilla.redhat.com/show_bug.cgi?id=2436950

https://access.redhat.com/security/cve/CVE-2026-25521

Details

Source: Mitre, NVD

Published: 2026-02-04

Updated: 2026-06-27

Risk Information

CVSS v2

Base Score: 6.8

Vector: CVSS2#AV:L/AC:L/Au:S/C:C/I:C/A:C

Severity: Medium

CVSS v3

Base Score: 8.8

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Severity: High

CVSS v4

Base 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

Severity: Critical

EPSS

EPSS: 0.00015