CVE

CVE-2026-4257

9.8

CVSScritical

Exploitable remotely over the internet · no authentication required.

Description

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.

Attack Vector

Network

Privileges Req.

None

User Interaction

None

contact form by supsystic

Updated Nov 10, 2026View on NVD →

S4E scanner

criticalProduct Based Web Vulnerabilities~10 seconds

WordPress Contact Form by Supsystic - Server-Side Template Injection

Contact Form by Supsystic WordPress plugin References: https://patchstack.com/database/vulnerability/wordpress-contact-form-by-supsystic-plugin-1-7-36-unauthenticated-server-side-template-injection-via-prefill-functionality-vulnerability https://plugins.trac.wordpress.org/browser/contact-form-by-supsystic/tags/1.7.36/modules/forms/views/forms.php#L323 https://plugins.trac.wordpress.org/changeset/3491826/contact-form-by-supsystic Remediation: Update to the latest version beyond 1.7.36.

url

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CVE history: contact form by supsystic

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