← Vulnerability feed

Vulnerability record · CVE-2026-25521 · published 4 February 2026

CVE-2026-25521: Locutus prototype pollution vulnerability

Locutus · Locutus

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.

9.4 CVSS 4.0 Critical EPSS 0.44% · top 63.9% CWE-1321 · Prototype pollutionCWE-915 · Mass assignment
9.4CVSS 4.0 base score
0.44%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
5References, 1 tagged exploit
15 Jul 2026Last modified by NVD

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.

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/locutusjs/locutus/commit/042af9ca7fde2ff599120783e720a17f335bb01c Patch
https://github.com/locutusjs/locutus/security/advisories/GHSA-rxrv-835q-v5mh ExploitVendor Advisory
https://access.redhat.com/security/cve/CVE-2026-25521
https://bugzilla.redhat.com/show_bug.cgi?id=2436950
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-25521.json

Track CVE-2026-25521 inside VULONE

Watch it alongside the ransomware crews, C2 infrastructure and forum chatter that reference it, query it through the API and pull it into your SIEM over TAXII.

Start free Open in platform

Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2026-32304Locutus code injection vulnerabilityLocutus brings stdlibs of other programming languages to JavaScript for educational purposes. Prior to 3.0.14, the create_function(args, code) functi…EPSS 0.82%9.8CVE-2020-7719Locutus prototype pollution vulnerabilityVersions of package locutus before 2.0.12 are vulnerable to prototype Pollution via the php.strings.parse_str function.EPSS 2.8%8.1CVE-2026-29091Locutus code injection vulnerabilityLocutus brings stdlibs of other programming languages to JavaScript for educational purposes. Prior to version 3.0.0, a remote code execution (RCE) f…EPSS 0.98%7.5CVE-2021-23392Locutus vulnerabilityThe package locutus before 2.0.15 are vulnerable to Regular Expression Denial of Service (ReDoS) via the gopher_parsedir function.EPSS 1.9%6.9CVE-2026-33993Locutus prototype pollution vulnerabilityLocutus brings stdlibs of other programming languages to JavaScript for educational purposes. Prior to version 3.0.25, the `unserialize()` function i…EPSS 0.75%6.3CVE-2026-33994Locutus prototype pollution vulnerabilityLocutus brings stdlibs of other programming languages to JavaScript for educational purposes. Starting in version 2.0.39 and prior to version 3.0.25,…EPSS 0.76%8.6CVE-2026-34621Adobe Acrobat Reader prototype pollution leads to code executionAdobe Acrobat and Reader (versions 24.001.30356, 26.001.21367 and earlier) are affected by prototype pollution (CWE-1321) that can result in arbitrar…KEVEPSS 2.2%analysed

Source: NIST National Vulnerability Database (record CVE-2026-25521), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.