Vulnerability Details CVE-2026-33994
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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.001
EPSS Ranking 26.3%
CVSS Severity
CVSS v3 Score 9.8
Products affected by CVE-2026-33994
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cpe:2.3:a:locutus:locutus:2.0.39
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cpe:2.3:a:locutus:locutus:3.0.0
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cpe:2.3:a:locutus:locutus:3.0.1
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cpe:2.3:a:locutus:locutus:3.0.10
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cpe:2.3:a:locutus:locutus:3.0.11
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cpe:2.3:a:locutus:locutus:3.0.12
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cpe:2.3:a:locutus:locutus:3.0.13
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cpe:2.3:a:locutus:locutus:3.0.14
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cpe:2.3:a:locutus:locutus:3.0.15
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cpe:2.3:a:locutus:locutus:3.0.16
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cpe:2.3:a:locutus:locutus:3.0.17
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cpe:2.3:a:locutus:locutus:3.0.18
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cpe:2.3:a:locutus:locutus:3.0.19
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cpe:2.3:a:locutus:locutus:3.0.2
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cpe:2.3:a:locutus:locutus:3.0.20
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cpe:2.3:a:locutus:locutus:3.0.21
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cpe:2.3:a:locutus:locutus:3.0.22
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cpe:2.3:a:locutus:locutus:3.0.23
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cpe:2.3:a:locutus:locutus:3.0.3
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cpe:2.3:a:locutus:locutus:3.0.4
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cpe:2.3:a:locutus:locutus:3.0.5
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cpe:2.3:a:locutus:locutus:3.0.6
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cpe:2.3:a:locutus:locutus:3.0.7
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cpe:2.3:a:locutus:locutus:3.0.8
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cpe:2.3:a:locutus:locutus:3.0.9