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TI-2026-03704 Aliases CVE-2026-4257GHSA-fgcr-fh9h-2fw9

Contact Form by Supsystic <= 1.7.36 - Unauthenticated Server-Side Template Injection via Prefill Functionality

Priority HIGH 77CWE-94Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Code execution
Confidentiality · integrity · availability
High · High · High
Fix status
No fix listed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-94.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.41475 98th percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
SupsysticContact Form by Supsysticup to 1.7.36—No fix listedCNA
  • Contact Form by Supsystic VendorSupsystic Affected up to 1.7.36 Fixed in — No fix listed CNA

Remediation

No fixed version listed by the sources yet.

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-4257
  2. 2026-10-03 Alias added: GHSA-fgcr-fh9h-2fw9

References

Other 3

  • TI-2023-02984 Supsystic Popup < 1.10.19 - Prototype Pollution CVSS 3.1CRITICAL 9.8
  • TI-2023-28011 WordPress Popup by Supsystic plugin <= 1.10.19 - Broken Access Control vulnerability CVSS 3.1CRITICAL 9.8
  • TI-2020-19380 WordPress Plugin Supsystic Digital Publications 1.6.9 Path Traversal XSS CVSS 4.0HIGH 8.7
  • TI-2020-19379 WordPress Plugin Supsystic Membership 1.4.7 SQL Injection via sidx CVSS 4.0HIGH 8.8
  • TI-2020-19378 WordPress Plugin Supsystic Pricing Table 1.8.7 SQL Injection XSS CVSS 4.0HIGH 8.8
  • TI-2020-19377 WordPress Plugin Supsystic Ultimate Maps 1.1.12 SQL Injection via sidx CVSS 4.0HIGH 8.8
See all 87 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences