CVE-2026-42753: WCFM Membership Auth Bypass Vulnerability

CVE-2026-42753 Overview

CVE-2026-42753 is a Missing Authorization vulnerability [CWE-862] in the WC Lovers WCFM Membership plugin (wc-multivendor-membership) for WordPress. The flaw stems from incorrectly configured access control security levels. Attackers can exploit the issue over the network without authentication or user interaction. The vulnerability affects WCFM Membership versions through <= 2.11.10. Patchstack published the advisory documenting the broken access control condition. The issue carries a CVSS 3.1 base score of 7.3, with low impact across confidentiality, integrity, and availability. The current EPSS probability is 0.036%, placing it in the 11th percentile for likelihood of exploitation activity.

Critical Impact
Unauthenticated remote attackers can invoke plugin functionality that should require authorization, potentially altering membership data, plans, or vendor configurations on affected WooCommerce multivendor sites.

Affected Products

WC Lovers WCFM Membership (wc-multivendor-membership) plugin for WordPress
All versions from initial release through 2.11.10
WooCommerce multivendor marketplaces using WCFM Membership for vendor subscription management

Discovery Timeline

2026-05-27 - CVE-2026-42753 published to NVD
2026-05-27 - Last updated in NVD database

Technical Details for CVE-2026-42753

Vulnerability Analysis

The vulnerability resides in the WCFM Membership plugin, which manages vendor membership plans for WooCommerce multivendor stores. One or more plugin actions fail to verify whether the requesting user holds the required capability or role before executing privileged operations. This pattern matches [CWE-862: Missing Authorization]. Because the attack vector is network based and requires no privileges or user interaction, any unauthenticated visitor can reach the affected endpoints. Successful exploitation results in low-impact effects across confidentiality, integrity, and availability, consistent with broken access control on a subset of plugin functions. The Patchstack advisory tracks the issue as a broken access control vulnerability in the plugin.

Root Cause

The root cause is the absence of capability checks (for example, current_user_can()) or nonce verification on one or more plugin handlers. The plugin relies on incorrectly configured access control security levels, which permits requests that should be restricted to vendors or administrators. See the Patchstack Vulnerability Report for the specific handler details.

Attack Vector

An unauthenticated attacker sends crafted HTTP requests to vulnerable WCFM Membership endpoints exposed by WordPress. Because authorization is not enforced, the server processes the request as if the caller were permitted. The attacker does not need valid credentials, multi-factor tokens, or social engineering to trigger the flaw. Refer to the Patchstack Vulnerability Report for endpoint-level technical detail.

Detection Methods for CVE-2026-42753

Indicators of Compromise

Unauthenticated HTTP POST or GET requests to wp-admin/admin-ajax.php invoking WCFM Membership actions from unfamiliar IP addresses.
Unexpected creation, modification, or deletion of vendor membership records, plans, or subscription metadata.
WordPress audit log entries showing privileged WCFM operations without a corresponding authenticated session.

Detection Strategies

Inspect web server access logs for repeated requests targeting WCFM Membership AJAX or REST routes lacking valid authentication cookies.
Compare current wp_options and WCFM-related database tables against known-good baselines to identify unauthorized changes.
Monitor WordPress core and plugin file integrity for tampering that may follow successful exploitation of access control flaws.

Monitoring Recommendations

Enable verbose logging on the WordPress installation and forward events to a centralized SIEM for correlation across vendor sites.
Alert on anomalous spikes in admin-ajax.php traffic without authenticated wordpress_logged_in_* cookies.
Track outbound requests from the web host that follow suspicious WCFM Membership calls, which may indicate post-exploitation activity.

How to Mitigate CVE-2026-42753

Immediate Actions Required

Identify all WordPress sites running WCFM Membership and confirm the installed version against 2.11.10.
Update the plugin to the latest available release that addresses the broken access control issue per the Patchstack advisory.
Restrict access to WordPress administrative and AJAX endpoints behind a web application firewall (WAF) until patching is complete.

Patch Information

Vendor remediation guidance is published through the Patchstack Vulnerability Report. Administrators should upgrade beyond version 2.11.10 once a fixed release is available and validate that vendor and membership workflows continue to function after the upgrade.

Workarounds

Temporarily disable the WCFM Membership plugin on production sites if a patched version is not yet deployable.
Apply WAF rules that block unauthenticated requests to WCFM Membership AJAX and REST endpoints.
Limit administrative and vendor dashboard access by IP allow list while validating patch availability.

bash

# Configuration example
# Identify installed WCFM Membership version via WP-CLI
wp plugin get wc-multivendor-membership --field=version

# Deactivate the plugin until a fixed version is installed
wp plugin deactivate wc-multivendor-membership

# After upgrading, verify the new version
wp plugin update wc-multivendor-membership
wp plugin get wc-multivendor-membership --field=version