CVE-2026-19709: Membership For WooCommerce Info Leak Flaw

CVE-2026-19709 Overview

CVE-2026-19709 is an authentication bypass vulnerability in the Membership For WooCommerce WordPress plugin versions before 3.1.2. The plugin fails to verify that an API consumer secret has actually been generated before comparing it against the value supplied in an incoming request. Unauthenticated attackers can reach the plugin's REST API routes on sites where the API feature was enabled but no keys were ever generated. Successful exploitation discloses any user's membership plan details. The issue is tracked under [CWE-287: Improper Authentication].

Critical Impact
Unauthenticated attackers can query REST endpoints and retrieve arbitrary users' membership plan details on affected WordPress sites.

Affected Products

Membership For WooCommerce WordPress plugin versions prior to 3.1.2
WordPress sites with the plugin's API feature enabled
Deployments where API keys were never generated after enabling the API

Discovery Timeline

2026-08-19 - CVE-2026-19709 published to NVD
2026-08-19 - Last updated in NVD database

Technical Details for CVE-2026-19709

Vulnerability Analysis

The Membership For WooCommerce plugin exposes REST API routes that require a consumer key and consumer secret for authentication. The authentication routine compares the submitted secret against the stored secret without first verifying that a secret has actually been generated. When the API is enabled but no keys have ever been created, the stored secret value is empty or unset. An attacker can supply an empty or matching value in the request and pass the comparison check.

Once authentication is bypassed, the attacker gains access to REST routes that expose membership plan data for any user. The vulnerability affects confidentiality only; no integrity or availability impact is present. The plugin was patched in version 3.1.2, which enforces a check that valid credentials exist before performing the comparison.

Root Cause

The root cause is missing precondition validation in the authentication handler. The code performs a direct comparison between the request-supplied secret and the stored value, without confirming that key generation has occurred. When both sides evaluate to empty or null, the comparison succeeds and the request is treated as authenticated.

Attack Vector

Exploitation requires network access to the target WordPress site with the plugin installed and the API feature toggled on, but with no API keys generated. The attacker crafts an HTTP request to the plugin's REST route supplying arbitrary or empty consumer credentials. No user interaction or prior privileges are required. See the WPScan Vulnerability Report for additional technical detail.

Detection Methods for CVE-2026-19709

Indicators of Compromise

Unexpected HTTP requests to Membership For WooCommerce REST routes from unfamiliar IP addresses
Access log entries showing REST API calls with empty or malformed consumer_key and consumer_secret parameters
Membership plan data queries in application logs without a corresponding authenticated session

Detection Strategies

Inventory WordPress installations for the Membership For WooCommerce plugin and identify versions below 3.1.2
Review plugin configuration to identify sites where the API is enabled but no keys have been generated
Correlate web server access logs against expected consumer application traffic patterns for the plugin's REST endpoints

Monitoring Recommendations

Enable verbose logging on WordPress REST API traffic and forward to a centralized log platform
Alert on unauthenticated or anomalous access to /wp-json/ routes belonging to the plugin
Track outbound data volume from WordPress hosts to detect bulk membership data extraction

How to Mitigate CVE-2026-19709

Immediate Actions Required

Upgrade the Membership For WooCommerce plugin to version 3.1.2 or later on all WordPress sites
Audit plugin API settings and disable the API where it is not required
Review recent access logs for suspicious REST API activity against the plugin's routes

Patch Information

The vendor released Membership For WooCommerce version 3.1.2, which adds a check that API credentials have been generated before performing the secret comparison. Administrators should update through the WordPress plugin management console or via WP-CLI. Confirm the installed version reads 3.1.2 or higher after the update.

Workarounds

Disable the plugin's API feature entirely until the patched version can be deployed
Generate and store valid API consumer keys so that the comparison no longer succeeds against empty input
Restrict access to /wp-json/ routes at the web server or WAF layer to trusted client IP addresses

bash

# Update the plugin via WP-CLI
wp plugin update membership-for-woocommerce --version=3.1.2
wp plugin get membership-for-woocommerce --field=version