cvedb.io
CVE-2026-4257
CRITICAL · CVSS 9.8
EPSS exploitation probability: 0%
Published 2026-03-30T22:16:20.313 · Last modified 2026-06-17T10:56:19.023

Summary

The Contact Form by Supsystic plugin for WordPress is vulnerable to Server-Side Template Injection (SSTI) leading to Remote Code Execution (RCE) in all versions up to, and including, 1.7.36. This is due to the plugin using the Twig `Twig_Loader_String` template engine without sandboxing, combined with the `cfsPreFill` prefill functionality that allows unauthenticated users to inject arbitrary Twig expressions into form field values via GET parameters. This makes it possible for unauthenticated attackers to execute arbitrary PHP functions and OS commands on the server by leveraging Twig's `registerUndefinedFilterCallback()` method to register arbitrary PHP callbacks.

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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.