CVE-2026-4257Contact Form by Supsystic <= 1.7.36 - Unauthenticated Server-Side Template Injection via Prefill Functionality
- 9.8CriticalCVSS base score
- 41.5%Exploitation in 30 daysEPSS · top 1.3% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- 3Public exploitsMetasploit, Nuclei and Exploit-DB
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.
Public exploit
An exploit or proof of concept is public: anyone can try it against an unpatched system. The public collections list a Metasploit module, a Nuclei template and an Exploit-DB entry for it.
Show the exploits3
Metasploit modules1 module
- Supsystic Contact Form Wordpress Plugin SSTI RCE (Metasploit module) (opens in a new tab)
exploit/multi/http/wp_plugin_supsystic_contact_form_rceRank excellentdisclosed 30 Mar 2026
Nuclei templates1 template
- WordPress Contact Form by Supsystic - Server-Side Template Injection (Nuclei template) (opens in a new tab)
http/cves/2026/CVE-2026-4257.yamlSeverity critical
Exploit-DB1 entry
- WordPress Plugin Supsystic Contact Form 1.7.36 - SSTI (Exploit-DB entry) (opens in a new tab)
EDB-ID 52564webapps, multiplepublished 14 May 2026Not verified
Modules, templates and exploits as listed by the Metasploit Framework (BSD-3-Clause), ProjectDiscovery's Nuclei templates (MIT) and the Exploit Database (GPLv2), read once a day. Where the data comes from
Timeline
ID reserved
By Wordfence
- 14 days later
· 14 days later
Published
- 9 days later
· 9 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| WordfenceCNA (assigner) | 3.1 | Critical9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| NVDNVD · Deferred | 3.1 | Critical9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 41.5% · top 1.3% of all CVEs (13 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: yes · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: Critical 9.8.
Affected products
supsysticcom · Contact Form by Supsystic
- affected ≤ 1.7.36
References
References3
- https://www.wordfence.com/threat-intel/vulnerabilities/id/415c9658-bfb2-453b-a697-c63c08b0ca61?source=cve (opens in a new tab)
- https://plugins.trac.wordpress.org/browser/contact-form-by-supsystic/tags/1.7.36/modules/forms/views/forms.php#L323 (opens in a new tab)
- https://plugins.trac.wordpress.org/changeset/3491826/contact-form-by-supsystic (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-17239 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-4257)Record last updated .