CVE-2026-3641: CWE-20 Improper Input Validation in appmaxplataforma Appmax
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.
AI Analysis
Technical Summary
CVE-2026-3641 describes an improper input validation vulnerability (CWE-20) in the Appmax WordPress plugin (versions up to 1.0.3). The plugin registers a public REST API webhook endpoint at /webhook-system that lacks any form of webhook signature validation, secret verification, or authentication mechanisms. Consequently, attackers can send unauthenticated webhook requests with malicious 'event' and 'data' parameters. This enables them to manipulate WooCommerce orders by changing statuses, creating new orders or products with attacker-controlled content, and modifying order metadata. The vulnerability is rated medium severity with a CVSS 3.1 base score of 5.3, reflecting its network attack vector, low attack complexity, no privileges required, and no user interaction needed. No patch or official fix is currently available, and the plugin is not a cloud service, so remediation depends on vendor updates or user mitigation.
Potential Impact
The vulnerability allows unauthenticated attackers to modify the integrity of WooCommerce data managed by the Appmax plugin. Specifically, attackers can change order statuses (processing, refunded, cancelled, pending), create new orders or products with arbitrary data, and write arbitrary values to order metadata. There is no direct impact on confidentiality or availability reported. The integrity of e-commerce transactions and product data is compromised, potentially leading to fraudulent orders, financial discrepancies, or manipulation of store inventory and order processing.
Mitigation Recommendations
No official patch or remediation is currently documented for this vulnerability. Since the plugin is not a cloud service, users must rely on vendor advisories for updates. Until a fix is available, it is recommended to disable or restrict access to the /webhook-system REST API endpoint to prevent unauthenticated requests. Implementing custom webhook validation or firewall rules to block unauthorized access may mitigate exploitation risk. Monitor the vendor's communications for any forthcoming patches or official guidance.
CVE-2026-3641: CWE-20 Improper Input Validation in appmaxplataforma Appmax
Description
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.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-3641 describes an improper input validation vulnerability (CWE-20) in the Appmax WordPress plugin (versions up to 1.0.3). The plugin registers a public REST API webhook endpoint at /webhook-system that lacks any form of webhook signature validation, secret verification, or authentication mechanisms. Consequently, attackers can send unauthenticated webhook requests with malicious 'event' and 'data' parameters. This enables them to manipulate WooCommerce orders by changing statuses, creating new orders or products with attacker-controlled content, and modifying order metadata. The vulnerability is rated medium severity with a CVSS 3.1 base score of 5.3, reflecting its network attack vector, low attack complexity, no privileges required, and no user interaction needed. No patch or official fix is currently available, and the plugin is not a cloud service, so remediation depends on vendor updates or user mitigation.
Potential Impact
The vulnerability allows unauthenticated attackers to modify the integrity of WooCommerce data managed by the Appmax plugin. Specifically, attackers can change order statuses (processing, refunded, cancelled, pending), create new orders or products with arbitrary data, and write arbitrary values to order metadata. There is no direct impact on confidentiality or availability reported. The integrity of e-commerce transactions and product data is compromised, potentially leading to fraudulent orders, financial discrepancies, or manipulation of store inventory and order processing.
Mitigation Recommendations
No official patch or remediation is currently documented for this vulnerability. Since the plugin is not a cloud service, users must rely on vendor advisories for updates. Until a fix is available, it is recommended to disable or restrict access to the /webhook-system REST API endpoint to prevent unauthenticated requests. Implementing custom webhook validation or firewall rules to block unauthorized access may mitigate exploitation risk. Monitor the vendor's communications for any forthcoming patches or official guidance.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- Wordfence
- Date Reserved
- 2026-03-06T16:04:14.223Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 69be1810f4197a8e3b78439f
Added to database: 3/21/2026, 4:01:20 AM
Last enriched: 4/9/2026, 6:49:10 PM
Last updated: 4/29/2026, 6:37:09 PM
Views: 38
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