# CVE-2026-33994

## Summary

- **CVE ID:** CVE-2026-33994
- **Severity:** MEDIUM
- **CVSS Score:** 9.8 (CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N)
- **CWE:** CWE-1321
- **Published:** Mar 27, 2026
- **Last Modified:** Apr 1, 2026

## Description

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.

## Affected Products

- locutusjs — locutus (>= 2.0.39, < 3.0.25)

## References

- [CNA](https://github.com/locutusjs/locutus/security/advisories/GHSA-vc8f-x9pp-wf5p)
- [CNA](https://github.com/locutusjs/locutus/pull/597)
- [CNA](https://github.com/locutusjs/locutus/commit/345a6211e1e6f939f96a7090bfeff642c9fcf9e4)
- [CNA](https://github.com/locutusjs/locutus/releases/tag/v3.0.25)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.56%
- **EPSS Percentile:** 44.7

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-11._