CVE-2026-3641

MEDIUM EPSS 21.6%
Published Mar 21, 20263mo ago · Modified Jun 17, 20262w ago
5.3 CVSS 3.1
Medium
Find Similar
Published Mar 21, 2026 3mo ago
Last Modified Jun 17, 2026 2w ago

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.

CVSS Details

Base Score
5.3
Exploitability
3.9
Impact
1.4
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality None
Integrity Low
Availability None

Threat Intelligence

EPSS Exploit Probability
21.6% percentile
Exploit & Patch Status
No Known Exploit
No Patch Available

Weaknesses 1

CWE-20 Improper Input Validation Validation

References 9

  • plugins.trac.wordpress.org https://plugins.trac.wordpress.org/browser/appmax/tags/1.0.3/includes/core/class-appmax-payments-webhook.php#L18
  • plugins.trac.wordpress.org https://plugins.trac.wordpress.org/browser/appmax/tags/1.0.3/includes/core/class-appmax-payments-webhook.php#L28
  • plugins.trac.wordpress.org https://plugins.trac.wordpress.org/browser/appmax/tags/1.0.3/includes/webhooks/class-appmax-payments-webhook-events.php#L103
  • plugins.trac.wordpress.org https://plugins.trac.wordpress.org/browser/appmax/tags/1.0.3/includes/webhooks/types/class-appmax-payments-order-paid.php#L56
  • plugins.trac.wordpress.org https://plugins.trac.wordpress.org/browser/appmax/trunk/includes/core/class-appmax-payments-webhook.php#L18
  • plugins.trac.wordpress.org https://plugins.trac.wordpress.org/browser/appmax/trunk/includes/core/class-appmax-payments-webhook.php#L28
  • plugins.trac.wordpress.org https://plugins.trac.wordpress.org/browser/appmax/trunk/includes/webhooks/class-appmax-payments-webhook-events.php#L103
  • plugins.trac.wordpress.org https://plugins.trac.wordpress.org/browser/appmax/trunk/includes/webhooks/types/class-appmax-payments-order-paid.php#L56
  • wordfence.com https://www.wordfence.com/threat-intel/vulnerabilities/id/6bf61bb7-f977-4afe-bb81-e6de12e00b03?source=cve

Remediation

No remediation data recorded yet

Check vendor advisories and the NVD entry for patch availability.