Pie Register Premium Plugin up to 3.8.4.0 on WordPress AJAX piereg_file_upload unrestricted upload

Summaryinfo

A vulnerability was found in Pie Register Premium Plugin up to 3.8.4.0. It has been rated as critical. This issue affects the function piereg_file_upload of the component AJAX Handler. This manipulation causes unrestricted upload. This vulnerability is handled as CVE-2026-84999. The attack can be initiated remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in Pie Register Premium Plugin up to 3.8.4.0. It has been declared as critical. Affected by this vulnerability is the function piereg_file_upload of the component AJAX Handler. The manipulation with an unknown input leads to a unrestricted upload vulnerability. The CWE definition for the vulnerability is CWE-434. The product allows the attacker to upload or transfer files of dangerous types that can be automatically processed within the product's environment. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

The Pie Register Premium plugin for WordPress is vulnerable to Unrestricted File Type Upload in all versions up to, and including, 3.8.4.0 via the piereg_file_upload function. This is due to the plugin performing file type validation via wp_check_filetype and wp_check_filetype_and_ext but never checking whether those validation calls produced errors before move_uploaded_file() is called, combined with no nonce or capability check on the AJAX handler. This makes it possible for unauthenticated attackers to upload files of dangerous types (e.g. PHP scripts) that may be executable, which makes remote code execution possible. The server returns the generated destination filename in the response, giving the attacker the exact path needed to trigger the uploaded file.

It is possible to read the advisory at wordfence.com. This vulnerability is known as CVE-2026-84999 since 09/02/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 10/28/2026). The attack technique deployed by this issue is T1608.002 according to MITRE ATT&CK.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Type

• WordPress Plugin

Name

• Pie Register Premium Plugin

Version

• 3.8.0
• 3.8.1
• 3.8.2
• 3.8.3
• 3.8.4.0

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CPE 2.2info

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