External risk intelligence

ARForms PHP Object Injection Allows File Deletion Data Retrieval or Code Execution

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2024-13784

The vulnerability exists in a WordPress plugin designed to handle contact forms, surveys, and popups. These components are intentionally placed on public-facing web pages to interact with site visitors, making the vulnerable input surface accessible to any unauthenticated user on the internet by design.

Deserialization

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

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

This advisory concerns a critical vulnerability in a popular WordPress plugin used for building forms. The issue, a PHP Object Injection, could allow unauthenticated attackers to compromise websites. While the vulnerability itself requires an additional component on the site to be fully exploitable, its presence in a widely used tool warrants attention to confirm relevance and assess potential exposure.

Unauthenticated code injection risk in WordPress forms.
Could impact any site using the affected plugin.
Confirm if your site uses this plugin and assess risk.

Attack Path

How an attacker could exploit the issue

An unauthenticated attacker can submit a specially crafted form to a WordPress site utilizing a vulnerable version of the ARForms plugin. This submission can lead to PHP Object Injection. While the plugin itself does not provide a viable chain for malicious actions, if another installed plugin or theme contains a known chain, the attacker could potentially delete files, steal data, or execute arbitrary code.

No authentication required.
Submitting malicious form data.
Potential code execution or data theft.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could allow unauthenticated attackers to inject a PHP Object into the system when processing form submissions. If another installed plugin or theme provides a usable POP chain, this could lead to arbitrary file deletion, sensitive data retrieval, or code execution.

Sensitive data or arbitrary files may be exposed.
Unauthenticated input injection via form submissions.
Code execution or data compromise.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability impacts WordPress sites using the ARForms plugin, potentially affecting their availability and data integrity. The primary responsibility for addressing this lies with the application owners and their respective platform or infrastructure teams who manage the WordPress instances. The immediate practical step is to identify all instances of the affected plugin, confirm their exposure and business criticality, and then coordinate with the vendor for a secure update.

Application owners must own the remediation.
Verify plugin reachability and business criticality.
Plan updates and coordinate with the vendor.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

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Frequently asked questions

What is the ARForms plugin for WordPress?

ARForms is a feature-rich WordPress plugin designed to help site owners create interactive elements like contact forms, surveys, quizzes, and pop-up builders. Because these tools are essential for collecting user feedback or capturing lead information, they are typically integrated directly into public-facing web pages where they can receive and process input from visitors.

What does PHP Object Injection mean for CVE-2024-13784?

This vulnerability, classified as CWE-502, occurs when an application improperly deserializes untrusted data. In this specific case, the plugin allows incoming form submission data to be processed as a PHP object without sufficient validation. This weakness creates a gateway that could allow an attacker to inject malicious objects into the application's memory if other conditions are met.

How does an attacker trigger this vulnerability?

An attacker triggers this flaw by submitting specially crafted data through the plugin's forms. Critically, the vulnerability does not manifest on its own; it requires the presence of a 'POP chain'—a sequence of code snippets found within other installed plugins or themes—to perform harmful actions. If no such chain exists on the system, the injected object cannot be leveraged to execute commands, delete files, or retrieve data.

Why is this vulnerability a concern for my WordPress site?

According to Halo Surface Signal, this plugin is designed to handle user-submitted content on public web pages, meaning the input surface is inherently accessible to anyone on the internet. Because the vulnerability does not require authentication, any site using an affected version of ARForms is theoretically reachable by external actors, making it important to assess your specific environment.

What should I do if I use the ARForms plugin?

Start by identifying all WordPress instances where the ARForms plugin is installed. Once you have a complete inventory, verify the plugin version to determine if it is affected. Your primary goal is to coordinate with the plugin vendor to secure an update or apply the appropriate patch, while also reviewing other installed themes and plugins to understand your overall system composition.

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.