CVE-2026-4109: Eventin Plugin Information Disclosure Flaw

CVE-2026-4109 Overview

The Eventin – Events Calendar, Event Booking, Ticket & Registration (AI Powered) plugin for WordPress contains a broken access control vulnerability due to an improper capability check on the get_item_permissions_check() function. This security flaw affects all versions up to and including 4.1.8, allowing authenticated attackers with minimal privileges to access sensitive order data.

Critical Impact

Authenticated attackers with Subscriber-level access can read arbitrary order data including customer PII (name, email, phone) by iterating order IDs, potentially leading to mass data exfiltration from WordPress sites using the vulnerable plugin.

Affected Products

• Eventin – Events Calendar, Event Booking, Ticket & Registration (AI Powered) plugin for WordPress versions up to and including 4.1.8

Discovery Timeline

• 2026-04-14 - CVE-2026-4109 published to NVD
• 2026-04-14 - Last updated in NVD database

Technical Details for CVE-2026-4109

Vulnerability Analysis

This vulnerability is classified as CWE-862 (Missing Authorization), a broken access control issue that occurs when the application fails to properly verify whether a user has the necessary permissions to perform a requested action. In the context of the Eventin plugin, the get_item_permissions_check() function does not adequately validate user capabilities before allowing access to order data through the REST API.

The vulnerability allows any authenticated user—including those with the lowest WordPress role (Subscriber)—to access order information that should be restricted to administrators or shop managers. By systematically iterating through order IDs, an attacker can enumerate and retrieve all order records in the database, exposing customer personally identifiable information (PII) including names, email addresses, and phone numbers.

Root Cause

The root cause of this vulnerability lies in the improper implementation of the get_item_permissions_check() function within the plugin's REST API endpoint handler. Instead of verifying that the requesting user has administrative or appropriate shop management capabilities, the function allows any authenticated user to pass the permission check. This design flaw violates the principle of least privilege and fails to implement proper role-based access control for sensitive order data.

Attack Vector

The attack is network-based and requires low privileges to execute. An attacker needs only a valid WordPress account with Subscriber-level access—the lowest authenticated role in WordPress. The attack requires no user interaction and can be automated to rapidly enumerate all order IDs and extract associated customer data.

The exploitation process involves:

1. Authenticating to the WordPress site with a Subscriber-level account
2. Identifying the vulnerable REST API endpoint used for retrieving order data
3. Systematically iterating through order IDs (e.g., starting from 1 and incrementing)
4. Collecting exposed PII from each successful response including customer names, email addresses, and phone numbers

This type of Insecure Direct Object Reference (IDOR) attack combined with missing authorization allows for complete enumeration of the order database without any rate limiting or permission barriers beyond basic authentication.

Detection Methods for CVE-2026-4109

Indicators of Compromise

• Unusual REST API requests to order endpoints from low-privileged user accounts (Subscribers)
• Sequential or patterned access to order IDs from a single user session
• High volume of order data retrieval requests that deviate from normal user behavior
• Web server access logs showing enumeration patterns against order-related API endpoints

Detection Strategies

• Monitor WordPress REST API access logs for requests to Eventin order endpoints from non-administrative user roles
• Implement detection rules for sequential order ID access patterns that indicate enumeration activity
• Alert on Subscriber-level accounts accessing order management API endpoints
• Review authentication logs for suspicious account creation followed by immediate API abuse

Monitoring Recommendations

• Enable detailed logging for WordPress REST API requests, particularly those involving the Eventin plugin endpoints
• Implement rate limiting on API endpoints to slow down enumeration attempts
• Configure alerts for anomalous data access patterns from low-privileged accounts
• Regularly audit user accounts with Subscriber role for suspicious activity patterns

How to Mitigate CVE-2026-4109

Immediate Actions Required

• Update the Eventin plugin to a version newer than 4.1.8 that includes the security patch
• Audit access logs for any signs of prior exploitation or data exfiltration
• Review and restrict user accounts with Subscriber-level access if not business-critical
• Consider temporarily disabling the Eventin plugin if immediate patching is not possible

Patch Information

A security patch addressing this vulnerability is available. The fix can be reviewed in the WordPress Plugin Changeset 3501510. Site administrators should update to the latest version of the Eventin plugin through the WordPress admin dashboard or by downloading directly from the WordPress plugin repository.

For additional technical details about this vulnerability, refer to the Wordfence Vulnerability Report.

Workarounds

• Restrict user registration on WordPress sites to prevent attackers from obtaining Subscriber-level accounts
• Implement additional access control at the web server level to limit API endpoint access to trusted IP addresses
• Use a Web Application Firewall (WAF) with rules to detect and block order ID enumeration attempts
• Temporarily disable REST API access for non-administrative users using security plugins until the patch is applied

# Example: Restrict REST API access in .htaccess (temporary workaround)
# Add to WordPress .htaccess file to limit API access
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{REQUEST_URI} ^/wp-json/eventin/ [NC]
RewriteCond %{REMOTE_ADDR} !^192\.168\.1\. [NC]
RewriteRule .* - [F,L]
</IfModule>