CVE-2026-4257: CWE-94 Improper Control of Generation of Code ('Code Injection') in supsysticcom Contact Form by Supsystic
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.
AI Analysis
Technical Summary
CVE-2026-4257 affects the Contact Form by Supsystic WordPress plugin through improper control of code generation (CWE-94). The plugin uses the Twig_Loader_String template engine without sandboxing, combined with the cfsPreFill feature that allows unauthenticated injection of Twig expressions into form fields via GET parameters. This enables attackers to execute arbitrary PHP code and OS commands remotely by leveraging Twig's registerUndefinedFilterCallback method. The vulnerability impacts all versions up to and including 1.7.36. The CVSS v3.1 base score is 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H), reflecting its critical impact and ease of exploitation without authentication.
Potential Impact
Successful exploitation results in remote code execution on the affected server, allowing attackers to run arbitrary PHP functions and operating system commands. This can lead to full compromise of the web server hosting the vulnerable plugin, including data theft, service disruption, or further network pivoting. The vulnerability requires no authentication and has a low attack complexity, making it highly dangerous.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, it is recommended to disable or remove the Contact Form by Supsystic plugin if possible. Restricting access to the vulnerable functionality or applying web application firewall rules to block malicious GET parameters may provide temporary mitigation. Monitor vendor channels for updates and apply patches promptly once released.
CVE-2026-4257: CWE-94 Improper Control of Generation of Code ('Code Injection') in supsysticcom Contact Form by Supsystic
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.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-4257 affects the Contact Form by Supsystic WordPress plugin through improper control of code generation (CWE-94). The plugin uses the Twig_Loader_String template engine without sandboxing, combined with the cfsPreFill feature that allows unauthenticated injection of Twig expressions into form fields via GET parameters. This enables attackers to execute arbitrary PHP code and OS commands remotely by leveraging Twig's registerUndefinedFilterCallback method. The vulnerability impacts all versions up to and including 1.7.36. The CVSS v3.1 base score is 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H), reflecting its critical impact and ease of exploitation without authentication.
Potential Impact
Successful exploitation results in remote code execution on the affected server, allowing attackers to run arbitrary PHP functions and operating system commands. This can lead to full compromise of the web server hosting the vulnerable plugin, including data theft, service disruption, or further network pivoting. The vulnerability requires no authentication and has a low attack complexity, making it highly dangerous.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, it is recommended to disable or remove the Contact Form by Supsystic plugin if possible. Restricting access to the vulnerable functionality or applying web application firewall rules to block malicious GET parameters may provide temporary mitigation. Monitor vendor channels for updates and apply patches promptly once released.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- Wordfence
- Date Reserved
- 2026-03-16T08:09:38.881Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 69caf0cde6bfc5ba1d72953b
Added to database: 3/30/2026, 9:53:17 PM
Last enriched: 4/14/2026, 3:08:57 PM
Last updated: 5/15/2026, 3:00:36 AM
Views: 167
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