CVE-2026-33993

Описание

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 applied. Version 3.0.25 patches the issue.

A flaw was found in Locutus, a library that integrates standard libraries from other programming languages into JavaScript. The unserialize() function, which converts serialized PHP data into JavaScript objects, fails to filter the __proto__ key during deserialization. A remote attacker can exploit this by providing a specially crafted PHP serialized payload that includes __proto__ as an array or object key. This vulnerability, known as prototype pollution, allows for property injection and can lead to a Denial of Service (DoS) by enabling attackers to override built-in JavaScript methods.