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.
Published: 2026-03-30
Score: 9.8 Critical
EPSS: 43.7% Moderate
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Impact

The Contact Form by Supsystic plugin for WordPress contains a Server‑Side Template Injection flaw that permits an unauthenticated attacker to inject and execute arbitrary Twig expressions. This vulnerability exposes the server to remote code execution, allowing execution of PHP functions and operating‑system commands. The weakness reflects code injection (CWE‑94).

Affected Systems

All WordPress installations using the Contact Form by Supsystic plugin version 1.7.36 or earlier are affected; the plugin is distributed by supsystic.com and is commonly embedded via their WordPress plugin.

Risk and Exploitability

The CVSS base score is 9.8, indicating critical severity. The EPSS score of 44% suggests a high likelihood of exploitation, and the vulnerability is not listed in the CISA KEV catalog. Attackers can exploit it over any public site without authentication by supplying crafted GET parameters to the prefill endpoint, triggering the Twig engine to process the injected template and run code. The exploitability is high and exhibits immediate remote code execution potential.

Generated by OpenCVE AI on May 15, 2026 at 14:42 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Upgrade Contact Form by Supsystic to the latest release (1.7.37 or later) where the SSTI flaw has been fixed.
  • If an upgrade cannot be performed immediately, disable or delete the plugin from the WordPress site to remove the vulnerability.
  • Implement a web application firewall rule that blocks or sanitises GET parameters containing Twig delimiters ({{ or }}) to prevent script injection until the plugin can be updated.

Generated by OpenCVE AI on May 15, 2026 at 14:42 UTC.

Tracking

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Advisories

No advisories yet.

History

Wed, 01 Apr 2026 02:15:00 +0000

Type Values Removed Values Added
First Time appeared Supsysticcom
Supsysticcom contact Form By Supsystic
Wordpress
Wordpress wordpress
Vendors & Products Supsysticcom
Supsysticcom contact Form By Supsystic
Wordpress
Wordpress wordpress

Tue, 31 Mar 2026 18:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Tue, 31 Mar 2026 03:00:00 +0000

Type Values Removed Values Added
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
References
Metrics cvssV3_1

{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}

Subscriptions

Supsysticcom Contact Form By Supsystic
Wordpress Wordpress
cve-icon MITRE

Status: PUBLISHED

Assigner: Wordfence

Published:

Updated: 2026-04-08T16:48:39.880Z

Reserved: 2026-03-16T08:09:38.881Z

Link: CVE-2026-4257

cve-icon Vulnrichment

Updated: 2026-03-31T16:13:47.315Z

cve-icon NVD

Status : Deferred

Published: 2026-03-30T22:16:20.313

Modified: 2026-04-24T18:11:16.583

Link: CVE-2026-4257

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-05-15T14:45:16Z

Weaknesses