CVE-2026-4257CRITICAL 9.8EPSS p98.5%

CVE-2026-4257CVE-2026-4257

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.

Scoring

CVSS 3.19.8 (CRITICAL)
VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS41.48% probability of exploitation · percentile 98.5% · 2026-06-18T12:00:27Z
Published2026-03-30
Last modified2026-04-24

Underlying weaknesses· 1

CWE-94

References

  1. https://plugins.trac.wordpress.org/browser/contact-form-by-supsystic/tags/1.7.36/modules/forms/views/forms.php#L323
  2. https://plugins.trac.wordpress.org/changeset/3491826/contact-form-by-supsystic
  3. https://www.wordfence.com/threat-intel/vulnerabilities/id/415c9658-bfb2-453b-a697-c63c08b0ca61?source=cve

1

TypeTargetConfidenceTier
WeaknessImproper Control of Generation of Code ('Code Injection')cwe-940%live

Related by meaning· 6

Nearest entities by semantic similarity across the cs-graph corpus.

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Sourced from NVD + FIRST.org EPSS. Curated for EU compliance use cases by Adam Lundqvist, Founder at SQUR.