CVE-2026-4257

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

CVSS 9.8 CRITICALEPSS 41.5%CWE-94

Vexday Risk Score

75Prioridad alta

Decisión SSVC (CISA)

Attend

PoC disponible → seguir de cerca

CVSS 9.8EPSS 41.5%KEV nãoPoC públicaNuclei simMetasploit simPatch —

Ciclo de vida

30 mar 2026Exploit Metasploit disponible

30 mar 2026Publicada en NVD

11 may 2026PoC pública

Recomendación: Planificar corrección próxima — ya existe PoC pública.

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:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Productos afectados

supsysticcom · Contact Form by Supsystic

PoCs públicas encontradas — 2

githubgithub.com/shootcannon/CVE-2026-4257★ 0 exploitdbwww.exploit-db.com/exploits/52564no verificado

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Referencias

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