Independent & educational platform Not a government body. No link or affiliation with any government organisation. Made for learning only. Test only systems you own or are authorised to test. Become a Partner or Sponsor → Full disclaimer

CVE-2026-33994

critical

Locutus brings stdlibs of other programming languages to JavaScript for educational purposes.

Vendor / product: Locutus — locutus

Locutus brings stdlibs of other programming languages to JavaScript for educational purposes. Starting in version 2.0.39 and prior to version 3.0.25, a prototype pollution vulnerability exists in the `parse_str` function of the npm package locutus. An attacker can pollute `Object.prototype` by overriding `RegExp.prototype.test` and then passing a crafted query string to `parse_str`, bypassing the prototype pollution guard. This vulnerability stems from an incomplete fix for CVE-2026-25521. The CVE-2026-25521 patch replaced the `String.prototype.includes()`-based guard with a `RegExp.prototype.test()`-based guard. However, `RegExp.prototype.test` is itself a writable prototype method that can be overridden, making the new guard bypassable in the same way as the original — trading one hijackable built-in for another. Version 3.0.25 contains an updated fix.

CVSS
9.8
9.8 (CVSS v3.1)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Severity source: NVD CVSS v3.1 (nvd@nist.gov)
Timeline (UTC)
Published: 2026-03-27 23:17
Modified: 2026-10-26 22:10
NVD status: Modified
Last synced 2 days ago
Verified against the source API 2026-10-27 07:07 UTC
Exploitation
Not listed in CISA KEV (as of last catalog sync)
Absence from KEV does not mean a CVE is not exploited. Exploitation status: unknown (no authoritative evidence in our sources).

Affected products

locutus / locutus ≥2.0.39 <3.0.25

Weakness classification (CWE)

CWE-1321

Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.

Mitigation & advisories

Vendor advisory: https://github.com/locutusjs/locutus/security/advisories/GHSA-vc8f-x9pp-wf5p
Vendor advisory: https://github.com/locutusjs/locutus/security/advisories/GHSA-vc8f-x9pp-wf5p
Vendor advisory: https://github.com/locutusjs/locutus/security/advisories/GHSA-vc8f-x9pp-wf5p
Vendor advisory: https://github.com/locutusjs/locutus/security/advisories/GHSA-vc8f-x9pp-wf5p
Vendor advisory: https://github.com/locutusjs/locutus/security/advisories/GHSA-vc8f-x9pp-wf5p
Vendor advisory: https://github.com/locutusjs/locutus/security/advisories/GHSA-vc8f-x9pp-wf5p
Vendor advisory: https://github.com/locutusjs/locutus/security/advisories/GHSA-vc8f-x9pp-wf5p
Vendor advisory: https://github.com/locutusjs/locutus/security/advisories/GHSA-vc8f-x9pp-wf5p
Patch / mitigation: https://github.com/locutusjs/locutus/commit/345a6211e1e6f939f96a7090bfeff642c9fcf9e4

References

Data sources

NVD CVE API 2.0 — fetched 2026-10-27 07:07 UTC · record ↗

Learn the basics

Understanding CVEs and CVSS Scores

Related CVEs

CVE-2026-33993