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CVE-2026-33993GHSA-4MPH-V827-F877

Locutus has Prototype Pollution via __proto__ Key Injection in unserialize()

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 3.0.25
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: poc
  • Automatable: yes
  • Technical impact: partial

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 applied. Version 3.0.25 patches the issue.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: poc · Automatable: yes · Technical impact: partial

  3. Record last updated

Affected versions

  • locutusjs locutus

    fixed in 3.0.25

  • locutusnpm

    fixed in 3.0.25

References 4

GitHub · locutusjs/locutus