PT-2026-29130 · Supsysticcom · Contact Form By Supsystic

Azril Fathoni · Published 2026-03-30 · Updated 2026-03-30 · CVE-2026-4257

NVD

CVSS v3.1

9.8

Critical

AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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.

Fix

Code Injection

Weakness Enumeration

CWE-94

Related Identifiers

CVE-2026-4257

Affected Products

Contact Form By Supsystic

References · 4

• https://nvd.nist.gov/vuln/detail/CVE-2026-4257 · Security Note
• https://plugins.trac.wordpress.org/browser/contact-form-by-supsystic/tags/1.7.36/modules/forms/views/forms.php#L323 · Note
• https://wordfence.com/threat-intel/vulnerabilities/id/415c9658-bfb2-453b-a697-c63c08b0ca61?source=cve · Note
• https://plugins.trac.wordpress.org/changeset/3491826/contact-form-by-supsystic · Note