CVE-2026-13171 Overview
CVE-2026-13171 is a broken access control vulnerability in the Eventin WordPress plugin versions before 4.1.20. The plugin's waiting-list registration handler fails to perform authorization checks. Unauthenticated attackers can create WordPress user accounts tied to arbitrary email addresses and inject fraudulent order records into the site database. The flaw is classified as [CWE-284] Improper Access Control and is exploitable remotely over the network without user interaction. Successful exploitation compromises data integrity across affected WordPress sites, enabling account creation abuse, spam campaigns, and pollution of event order data.
Critical Impact
Unauthenticated attackers can create arbitrary WordPress user accounts and inject fake order records into any site running a vulnerable version of the Eventin plugin.
Affected Products
- Eventin WordPress plugin versions prior to 4.1.20
- WordPress sites using the Eventin waiting-list registration feature
- Event management deployments relying on Eventin for attendee registration
Discovery Timeline
- 2026-08-12 - CVE-2026-13171 published to NVD
- 2026-08-12 - Last updated in NVD database
Technical Details for CVE-2026-13171
Vulnerability Analysis
The Eventin plugin exposes a waiting-list registration handler intended for prospective event attendees. The handler processes registration submissions and provisions user records tied to the supplied email address. It also writes corresponding order entries into the plugin's data store.
The handler does not validate the requester's identity or permissions before executing these actions. Any anonymous HTTP client can invoke the endpoint and supply arbitrary input. This turns a routine registration workflow into an unauthenticated account provisioning and data injection primitive.
The vulnerability affects data integrity most directly. Attackers can create accounts under email addresses they do not control, enabling spam, phishing preparation, or reputation attacks against the site owner. Injected order records may distort event analytics and expose the site to downstream logic flaws that trust order data.
Root Cause
The root cause is a missing authorization check on the waiting-list registration endpoint. The handler treats every request as legitimate, skipping capability verification, nonce validation, and rate limiting. This maps to [CWE-284] Improper Access Control.
Attack Vector
Exploitation requires a single unauthenticated HTTP request to the vulnerable waiting-list handler. The attacker supplies an arbitrary email address and event identifier. The plugin then creates a WordPress user account and writes an order record. No credentials, tokens, or user interaction are required. Refer to the WPScan Vulnerability Report for endpoint specifics.
Detection Methods for CVE-2026-13171
Indicators of Compromise
- Sudden spikes in newly registered WordPress user accounts with unfamiliar email addresses
- Order records in the Eventin database tied to users who never completed a legitimate checkout
- HTTP POST requests to the Eventin waiting-list registration endpoint from a small set of source IPs at high volume
- Outbound email bounces or spam complaints tied to email addresses not owned by the site's audience
Detection Strategies
- Review web server access logs for repeated POST requests targeting Eventin waiting-list registration routes under /wp-admin/admin-ajax.php or plugin REST endpoints
- Correlate WordPress user_register events with the absence of a corresponding authenticated session or referer
- Query the Eventin orders table for entries created without a matching payment or checkout event
Monitoring Recommendations
- Enable WordPress audit logging to capture user creation and plugin API activity
- Forward web and application logs to a centralized analytics platform for anomaly detection on registration bursts
- Alert on any registration handler receiving traffic without an authenticated session cookie
How to Mitigate CVE-2026-13171
Immediate Actions Required
- Update the Eventin plugin to version 4.1.20 or later on all WordPress sites
- Audit the wp_users table for accounts created since the plugin was installed and remove unauthorized entries
- Review Eventin order records for injected data and purge fraudulent entries
- Force password resets for any accounts that may have been provisioned without the owner's consent
Patch Information
The vendor addressed the missing authorization check in Eventin 4.1.20. The fix adds capability and nonce verification to the waiting-list registration handler. Details are documented in the WPScan Vulnerability Report.
Workarounds
- Disable the Eventin plugin until it can be updated to 4.1.20 or later
- Block public access to the waiting-list registration endpoint at the web application firewall (WAF) layer
- Restrict new user registration in WordPress general settings to reduce the impact of unauthorized account creation
# Example WAF rule to block anonymous requests to the vulnerable handler
# Adjust the path pattern to match your Eventin routes
SecRule REQUEST_URI "@rx /wp-admin/admin-ajax.php" \
"chain,deny,status:403,id:1013171,msg:'Block Eventin waiting-list abuse CVE-2026-13171'"
SecRule ARGS:action "@rx eventin_waitlist_register" \
"chain"
SecRule &REQUEST_COOKIES:/wordpress_logged_in_/ "@eq 0"
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
