CVSS 4.0
9.4 criticalCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:HCVE-2026-25521
Critical (9.4) in locutus locutus. EPSS 0.3% chance of exploitation in the next 30 days. Fixed in locutus 2.0.39.
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.
Severity
CVSS 3.1
8.8 highCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H- EPSS
- 0.3% chance of exploitation in the next 30 days; higher than 24% of CVEs (scores of 2026-10-31)
- CWEs
- CWE-1321, CWE-915
- Published
- Modified
- Record from
- the NVD, synced
Affected
- locutus:locutus
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-rxrv-835q-v5mh | npm | locutus | >=2.0.12 <2.0.39 | 2.0.39 |
References
- https://github.com/locutusjs/locutus/commit/042af9ca7fde2ff599120783e720a17f335bb01c
- https://github.com/locutusjs/locutus/security/advisories/GHSA-rxrv-835q-v5mh
- 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