External risk intelligence

WooCommerce Checkout Files Upload Arbitrary File Upload Leads to Remote Code Execution.

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-103688

The vulnerability affects a WooCommerce plugin designed for public-facing e-commerce websites. Checkout and file upload functionality in such plugins is intended to be accessible to site visitors and customers over the public internet by design, making the vulnerable endpoint inherently exposed in normal, intended use.

Unrestricted File Upload

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 vulnerability impacts a WooCommerce plugin, potentially allowing unauthorized file uploads. If exploited, this could lead to malicious code execution on affected servers. The primary concern is confirming if this plugin is in use and if the specific configuration that enables this vulnerability is active.

Unrestricted file uploads can enable code execution.
Affects e-commerce sites, a key customer touchpoint.
Verify plugin use and configuration for exposure.

Attack Path

How an attacker could exploit the issue

An attacker can upload malicious PHP files to a vulnerable WooCommerce site by exploiting the Checkout Files Upload plugin's weak file type validation. If the plugin is configured to accept all file types by leaving the accepted file types setting empty, unauthenticated users can upload arbitrary files. When the server executes PHP files from the uploads directory, this can lead to remote code execution.

Unauthenticated users can access the upload feature.
Uploading a PHP file when all types are accepted.
Remote code execution via uploaded PHP files.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could allow unauthenticated users to upload and execute arbitrary files, such as PHP scripts, on servers running the Checkout Files Upload for WooCommerce WordPress plugin when the file type validation is not configured. This could lead to the compromise of server-side code execution.

Server-side code execution.
Arbitrary file uploads.
Potential server compromise.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability in a WooCommerce plugin likely impacts application owners or teams responsible for website functionality. The initial step should be to identify all instances of the affected plugin, determine their exposure and criticality, and then engage with the accountable owner to plan remediation.

Application owners should own the issue.
Verify plugin reachability and business criticality first.
Plan remediation based on identified risk.

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 Checkout Files Upload for WooCommerce plugin?

This is a WordPress plugin designed for e-commerce sites to enable customers to upload files, such as custom designs or documents, during the checkout process. It helps businesses manage customer-provided assets directly through their online store interface.

What does CWE-434 mean regarding CVE-2026-103688?

CWE-434 identifies a weakness where software allows an attacker to upload files of dangerous types without sufficient verification. In this specific vulnerability, the plugin fails to restrict file extensions when its configuration is left empty, enabling the upload of executable scripts instead of intended customer documents.

How can an attacker trigger this vulnerability?

An attacker triggers the flaw by sending a malicious file, such as a PHP script, to the plugin's upload endpoint. This is only possible if the plugin's 'accepted file types' setting is left blank. If you have explicitly configured specific allowed file extensions, the system will reject unauthorized file types, preventing this specific attack path.

Is my site at risk according to Halo Surface Signal?

Yes, if you use this plugin, your site is likely at risk. Halo Surface Signal identifies that this plugin powers public-facing e-commerce checkout pages, which are designed to accept traffic from the internet. Because the vulnerable function is intended to be accessible to visitors, the attack surface is inherently exposed.

What steps should I take if I use this plugin?

First, verify if you have the affected version installed and confirm your 'accepted file types' configuration settings. If the field is empty, immediately restrict allowed file types to only necessary formats. Consult official vendor updates to apply patches that enforce stricter validation for all file uploads.

References

wpscan.com/vulnerability/08777aa1-6308-4e99-b2d0-5e43209aa6a6/

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.