CVE-2026-40776: WP Event Solution Auth Bypass Flaw

CVE-2026-40776 Overview

CVE-2026-40776 is an unauthenticated broken access control vulnerability affecting the WP Event Solution (Eventin) WordPress plugin in versions up to and including 4.1.8. The flaw is categorized under [CWE-862] Missing Authorization, allowing remote attackers to access functionality or data without proper permission checks.

The vulnerability is network-exploitable, requires no authentication, and needs no user interaction. Successful exploitation results in confidentiality impact on affected WordPress installations running the vulnerable plugin.

Critical Impact
Unauthenticated attackers can bypass access control checks in WP Event Solution to retrieve restricted data from WordPress sites running plugin versions 4.1.8 or earlier.

Affected Products

WP Event Solution (Eventin) WordPress plugin versions ≤ 4.1.8
WordPress sites with the vulnerable Eventin plugin installed and active
Any hosting environment exposing the plugin endpoints to the public internet

Discovery Timeline

2026-06-15 - CVE-2026-40776 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2026-40776

Vulnerability Analysis

The vulnerability stems from missing authorization checks in the WP Event Solution plugin. The plugin exposes functionality that should be restricted, but fails to verify whether the requesting user has the appropriate capability or role before processing the request.

Because the attack vector is the network and no authentication is required, attackers can issue HTTP requests directly to vulnerable plugin endpoints. The EPSS data indicates a probability of 0.414% with a percentile of 32.908, reflecting moderate exploitation likelihood relative to other published CVEs.

The impact is limited to information disclosure. The CVSS vector indicates no integrity or availability impact, meaning attackers cannot modify data or disrupt services through this specific flaw.

Root Cause

The root cause is a missing authorization check, classified as [CWE-862]. The plugin's request handlers do not invoke WordPress capability functions such as current_user_can() or equivalent permission validation before returning protected data.

This pattern commonly occurs when developers expose REST API routes or AJAX actions intended for administrative use but omit permission_callback validation or rely solely on nonce checks that an unauthenticated client can obtain.

Attack Vector

An attacker sends crafted HTTP requests to the exposed plugin endpoints on a target WordPress site. The plugin processes the request and returns data that should be restricted to authenticated or privileged users.

No credentials, social engineering, or local access is required. Refer to the Patchstack Vulnerability Report for endpoint-specific technical details.

Detection Methods for CVE-2026-40776

Indicators of Compromise

Anomalous unauthenticated HTTP GET or POST requests to /wp-json/ routes or admin-ajax.php actions registered by the Eventin plugin
Repeated requests to plugin endpoints from a single source IP without an associated WordPress authentication cookie
Outbound transfer of attendee, event, or organizer data records correlated with unauthenticated plugin requests

Detection Strategies

Inspect WordPress access logs for requests targeting Eventin REST routes that return non-empty JSON payloads to unauthenticated clients
Enable verbose logging on the WordPress REST API and correlate request paths against the installed plugin version using wp plugin list
Deploy a Web Application Firewall (WAF) rule set that flags Eventin plugin requests lacking valid session context

Monitoring Recommendations

Track plugin version inventory across all WordPress instances and alert on installations running Eventin ≤ 4.1.8
Monitor for spikes in 2xx responses from plugin endpoints originating from unauthenticated sessions
Forward WordPress and reverse proxy logs to a centralized analytics platform for retrospective hunting against the affected endpoints

How to Mitigate CVE-2026-40776

Immediate Actions Required

Update the WP Event Solution (Eventin) plugin to a version newer than 4.1.8 as soon as a fixed release is available from the vendor
Audit existing WordPress sites for the presence of the vulnerable plugin using wp plugin get wp-event-solution --field=version
Restrict public access to administrative and REST API endpoints via reverse proxy or WAF rules until patching is complete

Patch Information

Review the Patchstack Vulnerability Report for the current fixed version and vendor advisory. Apply the patched release through the WordPress plugin updater or by deploying the updated package files directly.

Workarounds

Deactivate the WP Event Solution plugin until a patched version is installed if event functionality is not business-critical
Implement WAF rules that block unauthenticated requests to the plugin's REST API namespace and AJAX actions
Restrict access to /wp-json/ routes belonging to the plugin via web server access controls or IP allowlisting

bash

# Example: block unauthenticated access to Eventin REST routes via nginx
location ~* /wp-json/eventin/ {
    if ($http_cookie !~* "wordpress_logged_in") {
        return 403;
    }
}