CVE-2026-4257
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.
Does this matter?
EPSS puts the probability of exploitation in the next 30 days at 41.5%, higher than 99% of all known CVEs. Patch or mitigate before the next change window.
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.
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 41.48% probability · 99th percentile
- Public exploits
- 1 in Exploit-DB · first 14 May 2026
- CISA KEV
- Not listed
- Weakness
- CWE-94
- Source
- security@wordfence.com
EPSS moved from 32.8% on 24 September 2026 to 41.5% on 30 October 2026. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”.
Public exploits (1)
Entries in Exploit-DB that cite this CVE. Links go to the Exploit-DB page and to the file in the public repository; nothing is hosted here. A verified tick means the Exploit-DB team confirmed the exploit works against the stated version.
References
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.