Review reviewCritical

CVE-2026-25521

locutusjs locutus, Logging Subsystem for Red Hat OpenShift

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: 9.4
EPSS: 0.26%
CISA KEV: Not listed
Published: 2026.02.05

PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV

Exploit probability0.26%

Technical severityCVSS 9.4

Vulnerability overview

Affected product and versions

Product: locutusjs locutus, Logging Subsystem for Red Hat OpenShift
Affected versions: >= >= 2.0.12, < 2.0.39, >= 2.0.12 < 2.0.39
Fixed versions: 2.0.39

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide

1
Identify
Confirm that locutusjs locutus, Logging Subsystem for Red Hat OpenShift and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS 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/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:X/V:X/RE:X/U:X
CWE: CWE-1321, CWE-915