CVE-2026-4257: The Contact Form by Supsystic plugin for WordPress is vulnerable to Server-Side Template Injection (SSTI) lead

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CRITICAL 9.8REMOTE

CVE-2026-4257 is a critical-severity flaw (CVSS 9.8) affecting affected software. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 parame

Why this priority

Critical severity
EPSS top 1%: very likely to be exploited
Public exploit reference
CISA SSVC: automatable with total technical impact
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	41.5% (top 1%)
CISA exploited list	No
Weakness	CWE-94
Published	2026-03-30
Last modified	2026-06-17

Publisher (CNA): Wordfence

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Timeline

2026-03-30 22:16 UTCPublished CVE record published
2026-06-17 10:56 UTCUpdated Record last modified

Exact fixes by distribution

Fedora ELN · perl-Encode · FIXED · 3.25-528.eln159 · FEDORA-2026-79991d0238 · source

sudo dnf upgrade --advisory=FEDORA-2026-79991d0238

Fedora 46 · fonttools · FIXED · 4.68.0-1.fc46 · FEDORA-2026-65d6c01c75 · source

sudo dnf upgrade --advisory=FEDORA-2026-65d6c01c75

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

GitHub PoC: dann3xplo1t/CVE-2026-4257 (1 stars)
GitHub PoC: bootstrapbool/cve-2026-4257 (0 stars)
GitHub PoC: shootcannon/CVE-2026-4257 (0 stars)
Exploit-DB: WordPress Plugin Supsystic Contact Form 1.7.36 - SSTI
Metasploit: Supsystic Contact Form Wordpress Plugin SSTI RCE
Nuclei scan template: WordPress Contact Form by Supsystic - Server-Side Template Injection

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-4257?

No fixed release is listed yet. Watch the vendor advisory and apply any mitigation shown on this page.

Is CVE-2026-4257 being exploited?

CVE-2026-4257 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-4257 affect?

CVE-2026-4257 affects affected software. Severity is critical (CVSS 9.8). 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_Lo

How urgent is CVE-2026-4257?

Priority 72/100. Critical severity; EPSS top 1%: very likely to be exploited; Public exploit reference; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action

Software pages

WordPress vulnerabilities

References

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