appmaxplataforma Appmax Plugin up to 1.0.3 on WordPress /webhook-system event/data input validation

Summaryinfo

A vulnerability marked as critical has been reported in appmaxplataforma Appmax Plugin up to 1.0.3 on WordPress. The affected element is an unknown function of the file /webhook-system. This manipulation of the argument event/data causes input validation. This vulnerability is tracked as CVE-2026-3641. The attack is possible to be carried out remotely. No exploit exists. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability has been found in appmaxplataforma Appmax Plugin up to 1.0.3 on WordPress and classified as critical. Affected by this vulnerability is an unknown code of the file /webhook-system. The manipulation of the argument event/data with an unknown input leads to a input validation vulnerability. The CWE definition for the vulnerability is CWE-20. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

The Appmax plugin for WordPress is vulnerable to Improper Input Validation in all versions up to, and including, 1.0.3. This is due to the plugin registering a public REST API webhook endpoint at /webhook-system without implementing webhook signature validation, secret verification, or any mechanism to authenticate that incoming webhook requests genuinely originate from the legitimate Appmax payment service. The plugin directly processes untrusted attacker-controlled input from the 'event' and 'data' parameters without verifying the webhook's authenticity. This makes it possible for unauthenticated attackers to craft malicious webhook payloads that can modify the status of existing WooCommerce orders (e.g., changing them to processing, refunded, cancelled, or pending), create entirely new WooCommerce orders with arbitrary data, create new WooCommerce products with attacker-controlled names/descriptions/prices, and write arbitrary values to order post metadata by spoofing legitimate webhook events.

The weakness was disclosed by Yoschanin Pulsirivong, Ronnachai Sretawat Na Ayutaya and Ronnachai Chaipha. The advisory is shared at wordfence.com. This vulnerability is known as CVE-2026-3641 since 03/06/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details are known, but no exploit is available.

Upgrading to version 1.0.3 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-14187). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Type

• WordPress Plugin

Vendor

• appmaxplataforma

Name

• Appmax Plugin

Version

• 1.0.0
• 1.0.1
• 1.0.2
• 1.0.3

CPE 2.3info

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CPE 2.2info

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If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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