CVE-2026-3296

Everest Forms <= 3.4.3 - Unauthenticated PHP Object Injection via Form Entry Metadata

2026-04-07 11:35
0xsabre

Strategic Overview

Status
Patched in 3.4.4
Affected Plugin
Everest Forms – Contact Form, Payment Form, Quiz, Survey & Custom Form Builder with AI
Affected Version
<= 3.4.3
CVSS
9.8Critical
Weakness type
CWE-502 · Deserialization of Untrusted Data
CVE
CVE-2026-3296
View all Everest Forms – Contact Form, Payment Form, Quiz, Survey & Custom Form Builder with AI vulnerabilities

At a glance

CVE-2026-3296 is a critical-severity Deserialization of Untrusted Data vulnerability in the Everest Forms WordPress plugin, affecting versions <= 3.4.3. It carries a CVSS score of 9.8 (reachable over the network; low attack complexity; high confidentiality, integrity, availability impact). Exploitation requires no authentication. The issue is fixed in version 3.4.4; sites on affected versions should update now. Disclosed April 2026, reported by 0xsabre.

Vulnerability Overview

The Everest Forms plugin for WordPress is vulnerable to PHP Object Injection in all versions up to, and including, 3.4.3 via deserialization of untrusted input from form entry metadata. This is due to the html-admin-page-entries-view.php file calling PHP's native unserialize() on stored entry meta values without passing the allowed_classes parameter. This makes it possible for unauthenticated attackers to inject a serialized PHP object payload through any public Everest Forms form field. The payload survives sanitize_text_field() sanitization (serialization control characters are not stripped) and is stored in the wp_evf_entrymeta database table. When an administrator views entries or views an individual entry, the unsafe unserialize() call processes the stored data without class restrictions.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no privileges on the target site, and no interaction from a victim user. A successful exploit has high impact on confidentiality, integrity, availability — full site compromise territory.

CWE-502: Deserialization of Untrusted Data

Everest Forms <= 3.4.3 carries this weakness at unserialize(), and reaching it takes no account at all. Deserialization of untrusted data means the application reconstructs objects from input a caller controls, letting the attacker choose which classes get instantiated and what their properties hold.

A workable chain turns deserialization into file writes, deletions or code execution, depending on what the loaded classes do in their magic methods. For Everest Forms the fix is 3.4.4: builds <= 3.4.3 are affected, anything from 3.4.4 onward is not.

Remediation

Update to version 3.4.4, or a newer patched version

How does WordSec protect against this?

Requests carrying this pattern arrive without a session, so nothing upstream of the firewall gets a chance to reject them: WordSec's web application firewall inspects request payloads before WordPress loads them. Classes like this one can leave something behind, so the staged malware scanner is the second half: it looks for dropped files and modified code rather than for the request that created them. None of that substitutes for the fix: Everest Forms 3.4.4 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Scanner
  • Login Security

External References

https://www.cve.org/CVERecord?id=CVE-2026-3296https://www.wordfence.com/threat-intel/vulnerabilities/id/2693ae37-790d-4b18-a9ec-054c8c27b8bchttps://nvd.nist.gov/vuln/detail/CVE-2026-3296

Related records

Vulnerability data © Defiant, Inc., provided under the Wordfence Intelligence T&C