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VulnerabilityPublished Updated

CVE-2026-4257: Contact Form by Supsystic (WordPress plugin) · Code Injection

Affects Contact Form by Supsystic (WordPress plugin)Source CVE Database V5

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Public exploit available (Metasploit, Exploit-DB) · 41% EPSS · CVSS 9.8 Critical.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
41.4% chance of exploitation in 30 days – higher than 98% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

t = 0 is the CVE’s publication on cve.org

  1. Disclosed: evidence found.

    CVE published 30 Mar 2026

  2. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  3. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

Timeline

  1. CVE ID reserved

    by Wordfence

    , 14 days before disclosure

  2. CVE published

    on cve.org

    , t = 0

  3. In Threat Radar

    record ingested

    , 27 minutes after disclosure

  4. First Exploit-DB entry (opens in a new tab)

    WordPress Plugin Supsystic Contact Form 1.7.36 - SSTI

    , 45 days after disclosure

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
supsysticcomContact Form by SupsysticAffected
  • <=1.7.36
Fixed in–

AI-suggested

Until an official fix is available, it is recommended to disable or remove the Contact Form by Supsystic plugin if possible. Restricting access to the vulnerable functionality or applying web application firewall rules to block malicious GET parameters may provide temporary mitigation. Monitor vendor channels for updates and apply patches promptly once released.

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.

References

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