Contact Form by Supsystic: Code execution
Contact Form by Supsystic is affected by code execution. The vulnerable path is reachable without authentication. Successful exploitation can run attacker-controlled code in the WordPress hosting account. The published affected range is <= 1.7.36.
- Component
- Contact Form by Supsystic
- Plugin slug
contact-form-by-supsystic- Affected
- <= 1.7.36
- Safe version
> 1.7.36- Published
- Mar 30, 2026
This CVE was published Mar 30, 2026 and is one of 7 known issues for this plugin.
Update, patch or deactivate.
Update Contact Form by Supsystic to a release after 1.7.36, or disable and remove it until a fixed version is available.
A safe version is available, so updating to that version or later is the preferred remediation. If an immediate update is not practical, consider a targeted application patch or temporarily restricting the affected functionality.
Deactivate only when warranted by your risk profile, or when advised by your hosting provider in the limited circumstances where the vulnerability cannot otherwise be mitigated. If you’re unsure which action is appropriate, contact Fused or your hosting provider for guidance.
Technical 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.
CVE / CNA vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H