External risk intelligence

WS Form LITE WordPress Plugin PHP Object Injection Vulnerability

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-4703

The vulnerability exists in a WordPress plugin designed to handle form submissions. Such plugins are typically deployed on public-facing websites to interact with visitors, making the vulnerable input path accessible over the internet by design.

Deserialization

Halo Surface Signal: 4 out of 5 — likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A security vulnerability has been identified in a WordPress plugin used for contact forms, potentially allowing unauthorized users to inject malicious code. While the vulnerability itself requires an additional condition (a specific type of code to be present from another plugin or theme) to cause harm, its presence could lead to severe consequences such as data theft, file deletion, or code execution if that condition is met. The main concern at this stage is confirming if this specific plugin is in use and if the necessary conditions for exploitation exist within your environment.

Unauthenticated code injection in a form builder plugin.
Impact depends on other installed code; may enable severe actions.
Confirm relevance and potential exposure of this plugin.

Attack Path

How an attacker could exploit the issue

An unauthenticated attacker can submit a form to trigger a PHP Object Injection vulnerability in the WS Form LITE plugin. This occurs when the plugin deserializes untrusted input from form submission meta values. While the plugin itself doesn't provide a direct exploit chain, if other installed plugins or themes contain a suitable PHP Object (POP) chain, the attacker could potentially achieve significant impact, such as file deletion, data retrieval, or code execution.

Attacker can submit a form.
Vulnerable input is deserialized from form meta.
Impact depends on other installed plugins/themes.

Live Threat

Current exploitation, exposure, and threat context

When supported by an installed theme or plugin containing a POP chain, this vulnerability could allow unauthenticated attackers to inject PHP objects through form submission meta values. This could potentially lead to actions such as deleting files, retrieving sensitive data, or executing arbitrary code on the server.

Unauthenticated PHP Object Injection.
Via untrusted input in form submission.
Arbitrary code execution or data retrieval.

Operational Fix

Recommended remediation, mitigation, and detection steps

The WS Form LITE plugin's PHP Object Injection vulnerability requires an additional plugin or theme with a POP chain to be exploited for significant impact. Responsibility for remediation likely falls to the team managing the WordPress application and its plugins, potentially involving coordination with content owners or the vendor if direct fixes are unavailable. The initial practical step is to identify all WordPress sites using this plugin, confirm if any other plugins or themes with POP chains are installed, and then assess the risk to determine the appropriate remediation plan, which may include vendor engagement or temporary mitigating controls.

Identify WordPress sites with the plugin.
Verify presence of POP chain plugins/themes.
Plan remediation with accountable owner.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

What is the WS Form LITE plugin for WordPress?

WS Form LITE is a tool used on WordPress sites to create and manage custom forms, such as contact or lead generation forms. It allows site administrators to build interactive fields that visitors fill out, which are then processed by the plugin to handle data submissions on the server.

What is PHP Object Injection in CVE-2026-4703?

This is a security weakness, classified as CWE-502, where a program improperly handles untrusted data during deserialization. In this case, the plugin processes data submitted through forms in a way that allows an attacker to inject unauthorized PHP objects into the application memory.

How can an attacker trigger this vulnerability?

An attacker can trigger this by submitting a specially crafted form value. Importantly, the vulnerability alone does not grant control; it only becomes harmful if your WordPress site also has another installed plugin or theme that contains a 'POP chain'—a specific set of code the attacker can hijack to perform malicious actions.

Is my site at risk according to Halo Surface Signal?

Halo Surface Signal identifies this as a likely risk because WS Form LITE is designed to be internet-facing. Since the plugin is meant to interact with public visitors, the vulnerable input path is exposed to the internet by design, making it reachable by any remote user.

What should I do if I run WS Form LITE?

First, confirm if your WordPress environment uses versions up to 1.10.80. Next, perform an inventory of all other plugins and themes installed on those sites, as the impact of this bug depends entirely on the presence of additional code containing a POP chain. Coordinate with your site administrators to assess these dependencies and determine your remediation strategy.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.