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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History
Tue, 31 Mar 2026 03:00:00 +0000
| Type | Values Removed | Values Added |
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| 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. | |
| Title | Contact Form by Supsystic <= 1.7.36 - Unauthenticated Server-Side Template Injection via Prefill Functionality | |
| Weaknesses | CWE-94 | |
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cvssV3_1
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Status: PUBLISHED
Assigner: Wordfence
Published:
Updated: 2026-03-30T21:26:10.228Z
Reserved: 2026-03-16T08:09:38.881Z
Link: CVE-2026-4257
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Status : Received
Published: 2026-03-30T22:16:20.313
Modified: 2026-03-30T22:16:20.313
Link: CVE-2026-4257
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OpenCVE Enrichment
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