Is CVE-2026-4257 actively exploited?

A proof-of-concept exploit is publicly available for CVE-2026-4257, but active exploitation has not been confirmed.

Can CVE-2026-4257 be exploited remotely?

Yes. CVE-2026-4257 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2026-4257?

CVE-2026-4257 has a CVSS score of 9.8 (CRITICAL).

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CRITICALPOC

CVE-2026-4257

CWE-94Published: March 30, 2026· Updated: Apr 1, 2026

9.8

CVSS v3.1

EPSS:12.78%probability of exploitation in 30 daysPercentile:94.0th

Official 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.

NVD Source

Technical Analysis

CVE-2026-4257 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.

A proof-of-concept (PoC) exploit exists for CVE-2026-4257. While not yet confirmed in active campaigns, the availability of PoC code increases exploitation risk substantially.