CVE-2026-4257

critical · 9.8

A public exploit / detection template exists

Weaponised detection is publicly available, which meaningfully raises real-world risk regardless of CVSS. nuclei-templates →

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.

9.8

CVSS

41.5%

EPSS (exploit prob.)

99th

EPSS percentile

2026-03-30

Published

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

Weaknesses

CWE-94

References

Query this programmatically:

curl https://evil-db.io/api/v1/cve/CVE-2026-4257