CVE-2026-4257 | The Contact Form by Supsystic plugin for WordPress is vulner… | CVSS 9.8 CRITICAL

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.

Metadata

CVE ID: CVE-2026-4257
State: PUBLISHED
Assigner: Wordfence
Reserved: 2026-03-16 08:09 UTC
Published: 2026-03-30 21:26 UTC
Last updated: 2026-04-08 16:48 UTC
Primary CWE: CWE-94
CWE-94 Improper Control of Generation of Code ('Code Injecti…
Vendor / Product: supsysticcom / Contact Form by Supsystic
Sources: cve.org · NVD

Severity & Metrics

9.8 CRITICAL CVSS 3.1

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

SSVC — CISA Coordinator

Exploitation: none
Automatable: yes
Tech. Impact: total

Affected products (1)

Vendor	Product	Platform	Versions
supsysticcom	Contact Form by Supsystic	—	0 ≤ 1.7.36

Weakness (CWE)

CWE	Source	Description
CWE-94	cna	CWE-94 Improper Control of Generation of Code ('Code Injection')

CVSS scores (1)

Score	Severity	Version	Source	Vector
9.8	CRITICAL	3.1	cna	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References (3)