CVE-2026-25521
HIGHDescription
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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Exploit Intelligence
Moderate risk: more likely to be exploited than 41% of all known CVEs.
References
Related Vulnerabilities
Other CWE-1321 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2019-0230 | Critical | 9.8 | 97% | - | - |
| CVE-2019-11358 | Medium | 6.1 | 87% | - | Fix |
| CVE-2020-7774 | High | 7.3 | 69% | - | Fix |
| CVE-2022-24760 | Critical | 10.0 | 49% | - | Fix |
| CVE-2022-39396 | Critical | 9.8 | 39% | - | Fix |
| CVE-2022-2564 | Critical | 9.8 | 33% | - | Fix |
Common questions
How do I fix CVE-2026-25521?
Upgrade locutus to 2.0.39 or later.
Is CVE-2026-25521 being actively exploited?
Not that we know of. CVE-2026-25521 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.50% is the estimated probability that it will be exploited in the next 30 days. That is higher than 41% of all scored CVEs.
How severe is CVE-2026-25521?
CVE-2026-25521 has a CVSS v3 base score of 8.8, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-25521 affect?
Published advisories record a fix for locutus (npm). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
Embed a live status badge for CVE-2026-25521
Markdown
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-15.