CVE-2026-14558

User Frontend – Membership, User Registration, User Profile, User Directory & Content Restriction with Frontend Post Submission < 4.3.10 - Authenticated (Editor+) PHP Object Injection

2026-08-28 00:00
Hijun Kim

At a glance

CVE-2026-14558 is a medium-severity Deserialization of Untrusted Data vulnerability in the User Frontend WordPress plugin, affecting versions < 4.3.10. It carries a CVSS score of 6.6 (reachable over the network; high confidentiality, integrity, availability impact). Exploitation requires an authenticated account at Editor level or above. The issue is fixed in version 4.3.10; sites on affected versions should update now. Disclosed August 2026, reported by Hijun Kim.

Vulnerability Overview

The User Frontend – Membership, User Registration, User Profile, User Directory & Content Restriction with Frontend Post Submission plugin for WordPress is vulnerable to PHP Object Injection in all versions up to 4.3.10. This is due to deserialization of untrusted input. This makes it possible for authenticated attackers, with editor-level access and above, to inject a PHP Object. No known POP chain is present in the vulnerable software. If a POP chain is present via an additional plugin or theme installed on the target system, it could allow the attacker to delete arbitrary files, retrieve sensitive data, or execute code.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, 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

Reaching this weakness in User Frontend < 4.3.10 takes an account at Editor level or above. 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 User Frontend the fix is 4.3.10: builds < 4.3.10 are affected, anything from 4.3.10 onward is not.

Remediation

Update to version 4.3.10, or a newer patched version

How does WordSec protect against this?

An attacker needs Editor access first, so the firewall sees the attempt as traffic from a logged-in account: 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: User Frontend 4.3.10 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Scanner
  • Alerts

External References

Related records

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