WordPress security changelog
MEDIUM CVE-2026-3641 Deferred

Appmax: A security weakness

Appmax is affected by a security weakness. The vulnerable path is reachable without authentication. The resulting impact depends on how the affected component exposes the vulnerable operation.

CVE / CNA score 5.3 CVSS 3.1 · security@wordfence.com
NVD score Pending NVD has not published its own CVSS assessment.
Component
Appmax
Plugin slug
appmax
Affected
See vendor advisory
Safe version
See mitigation notes
Published
Mar 21, 2026
Weakness
CWE-20 — Improper Input Validation

This CVE was published Mar 21, 2026 and is one of 1 known issue for this plugin.

What to do

Update, patch or deactivate.

Update Appmax to a release outside the affected range, or disable and remove it until a fixed version is available.

No confirmed safe version is listed. Consider a vendor-supported patch or temporarily restricting the affected functionality while you assess the risk.

Deactivate only when warranted by your risk profile, or when advised by your hosting provider in the limited circumstances where the vulnerability cannot otherwise be mitigated. If you’re unsure which action is appropriate, contact Fused or your hosting provider for guidance.

Source record

Technical 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.

CVE / CNA vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

References

Primary and upstream sources