CVE-2026-31919: Advanced Coupons Auth Bypass Vulnerability

CVE-2026-31919 Overview

A Missing Authorization vulnerability has been identified in the Advanced Coupons for WooCommerce Coupons plugin developed by Josh Kohlbach. This WordPress plugin vulnerability allows attackers to exploit incorrectly configured access control security levels, potentially enabling unauthorized access to restricted functionality within WooCommerce coupon management systems.

Critical Impact

Authenticated attackers with low-level privileges can bypass authorization controls to access sensitive coupon information that should be restricted to higher-privileged users, potentially exposing business-critical discount configurations and customer data.

Affected Products

• Advanced Coupons for WooCommerce Coupons (advanced-coupons-for-woocommerce-free) versions up to and including 4.7.1
• WordPress installations running the vulnerable plugin versions
• WooCommerce stores utilizing the Advanced Coupons extension

Discovery Timeline

• 2026-03-13 - CVE-2026-31919 published to NVD
• 2026-03-16 - Last updated in NVD database

Technical Details for CVE-2026-31919

Vulnerability Analysis

This vulnerability is classified under CWE-862 (Missing Authorization), indicating that the plugin fails to properly verify that a user has the required permissions before allowing access to certain functionality or data. The attack requires network access and low-level authentication (such as a subscriber or customer account), but no user interaction is needed for successful exploitation.

The vulnerability allows authenticated users to access information that should be restricted based on their role capabilities. While the impact is limited to confidentiality exposure without the ability to modify data or cause service disruption, it nonetheless represents a significant access control weakness in e-commerce environments where coupon strategies and discount codes often contain sensitive business information.

Root Cause

The root cause of this vulnerability lies in missing or improperly implemented authorization checks within the Advanced Coupons for WooCommerce Coupons plugin. When processing requests to coupon-related functionality, the plugin fails to verify that the authenticated user possesses the appropriate WordPress capabilities or role requirements before returning sensitive information.

WordPress plugins should implement proper capability checks using functions like current_user_can() to validate user permissions before exposing restricted data. In this case, the absence of such checks allows lower-privileged users to access data intended only for administrators or shop managers.

Attack Vector

The vulnerability is exploited over the network by an authenticated attacker with minimal privileges. The attack flow involves:

1. An attacker creates or obtains access to a low-privileged WordPress account (subscriber, customer, or similar role)
2. The attacker identifies endpoints or functionality within the Advanced Coupons plugin that handle coupon data
3. By directly accessing these endpoints, the attacker bypasses the intended role-based access controls
4. Sensitive coupon information is disclosed to the unauthorized user

Since no specific proof-of-concept code is available for this vulnerability, technical details regarding the exact vulnerable endpoints and parameters should be referenced from the Patchstack Vulnerability Report.

Detection Methods for CVE-2026-31919

Indicators of Compromise

• Unusual access patterns to coupon-related AJAX endpoints or REST API routes from low-privileged user accounts
• Subscriber or customer role accounts accessing admin-only coupon data or configuration pages
• Unexpected HTTP requests to Advanced Coupons plugin endpoints from accounts without shop_manager or administrator capabilities
• Log entries showing successful data retrieval from coupon management functions by non-administrative users

Detection Strategies

• Implement WordPress audit logging to track user access to coupon management functionality and compare against expected role permissions
• Monitor web server access logs for requests to /wp-admin/admin-ajax.php with Advanced Coupons-specific action parameters from non-admin users
• Deploy web application firewall (WAF) rules to detect and alert on broken access control patterns targeting WooCommerce plugin endpoints
• Use SentinelOne Singularity XDR to correlate WordPress application logs with endpoint telemetry for comprehensive threat detection

Monitoring Recommendations

• Enable detailed WordPress activity logging with plugins that capture user capability checks and permission-related events
• Configure alerting for any access to coupon management functions by users without explicit administrator or shop_manager roles
• Regularly audit user accounts to identify any unexpected privilege escalation or suspicious role assignments

How to Mitigate CVE-2026-31919

Immediate Actions Required

• Update Advanced Coupons for WooCommerce Coupons to a version newer than 4.7.1 once a patch is available
• Audit existing WordPress user accounts and remove unnecessary accounts or reduce privileges where appropriate
• Review recent access logs to identify any potential exploitation attempts prior to patching
• Consider temporarily deactivating the plugin if business operations permit until a patched version is released

Patch Information

A patched version addressing this Missing Authorization vulnerability should be obtained from the official WordPress plugin repository or the vendor directly. Monitor the Patchstack Vulnerability Report for updates on remediation status and patch availability.

Administrators should always verify plugin updates from trusted sources and maintain regular backup procedures before applying security patches.

Workarounds

• Restrict WordPress user registration and limit the creation of new accounts to reduce the attack surface for authenticated exploitation
• Implement additional access control layers using WordPress security plugins that provide capability-based restrictions on AJAX and REST API endpoints
• Use a Web Application Firewall (WAF) to filter and monitor requests to sensitive plugin endpoints
• Apply the principle of least privilege by ensuring only necessary users have accounts and appropriate role assignments

# WordPress configuration hardening
# Add to wp-config.php to disable user registration if not required
define('DISABLE_WP_CRON', false);

# Ensure proper file permissions on WordPress installation
find /var/www/html/wp-content/plugins -type f -exec chmod 644 {} \;
find /var/www/html/wp-content/plugins -type d -exec chmod 755 {} \;

# Review and audit current user roles (run via WP-CLI)
wp user list --fields=ID,user_login,roles --format=table