Critical 9.8Published Mar 30, 2026

CVE-2026-4257Contact Form by Supsystic <= 1.7.36 - Unauthenticated Server-Side Template Injection via Prefill Functionality

Updated under an hour ago (Oct 26, 2026, 10:23 PM ET)

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No exploitation reported and no EPSS estimate yet.

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Every CVE for supsysticcom Contact Form by Supsystic

Exploited in the last 30 days

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.

CVSS: 9.8 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness (CWE): CWE-94
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Wordfence
NVD analysis: Deferred
Record last updated: Apr 8, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

supsysticcom Contact Form by Supsystic supsysticcom:contact_form_by_supsystic (from the name)	through 1.7.36	CNA record

References

References

https://www.wordfence.com/threat-intel/vulnerabilities/id/415c9658-bfb2-453b-a697-c63c08b0ca61?source=cve
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

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.