CVE-2026-4257

CVE-2026-4257 vulnerability

CVSS

9.8

EPSS

41.5%

EPSS pct

99th

Exploited

No known

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.

Affected vendor

See references

Affected product

See references

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Weakness type (CWE)

CWE-94 — Code Injection

Published

2026-03-30

Risk analysis

Based on its CVSS vector, this vulnerability is exploitable over the network, low attack complexity, requiring no privileges, no user interaction. Successful exploitation leads to high impact to confidentiality, high impact to integrity, high impact to availability.

Its EPSS score of 41.5% reflects a moderate probability of exploitation activity in the wild over the next 30 days, placing it among the most exploited CVEs currently tracked.

Check your external exposure to CVE-2026-4257

Confirm whether the affected software is running on any internet-facing host or subdomain.
Match discovered service fingerprints against the version affected by CVE-2026-4257.
Prioritise remediation if the asset is public, business-critical, or near authentication/payment flows.

How ThreatPort helps with CVE-2026-4257

ThreatPort's external attack surface scanner checks your internet-facing assets — agentlessly, from the outside in — for the exposed services and versions that CVE-2026-4257 affects, then prioritises the finding by real risk using CISA KEV and FIRST.org EPSS.

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