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CVE-2026-33993
CRITICAL · CVSS 9.8
EPSS exploitation probability: 0%
Published 2026-03-27T23:17:14.237 · Last modified 2026-06-17T10:38:23.947

Summary

Locutus brings stdlibs of other programming languages to JavaScript for educational purposes. Prior to version 3.0.25, the `unserialize()` function in `locutus/php/var/unserialize` assigns deserialized keys to plain objects via bracket notation without filtering the `__proto__` key. When a PHP serialized payload contains `__proto__` as an array or object key, JavaScript's `__proto__` setter is invoked, replacing the deserialized object's prototype with attacker-controlled content. This enables property injection, for...in propagation of injected properties, and denial of service via built-in method override. This is distinct from the previously reported prototype pollution in `parse_str` (GHSA-f98m-q3hr-p5wq, GHSA-rxrv-835q-v5mh) — `unserialize` is a different function with no mitigation a

Affected products

locutus — locutus

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References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.