Eventin 4.0.26 - 4.1.15 - Missing Authorization to Unauthenticated Payment Bypass via REST API
The Eventin – Event Calendar, Event Registration, Tickets & Booking (AI Powered) plugin for WordPress is vulnerable to authorization bypass due to a regression in versions from 4.0.26 up to and including 4.1.15. This is due to the plugin not properly verifying that a user is authorized to perform an action in the payment_complete() function of PaymentController.php. This makes it possible for unauthenticated attackers to mark unpaid ticket orders as completed by submitting a fabricated SureCart checkout ID or FluentCart cart hash, granting themselves paid event access, QR-code attendee tickets, and order confirmation emails without making any real payment. The wp_rest nonce required to reach the vulnerable endpoint is embedded in every public event page, meaning no WordPress session or credentials are needed to obtain it. This vulnerability represents a regression — the same function and endpoint were previously patched but the fix did not persist through subsequent releases.
Quick answer
Eventin – Event Calendar, Event Registration, Tickets & Booking (AI Powered) should be reviewed and updated if it matches the affected versions. The recommended fix is to apply the vendor-supported patched version or the mitigation steps below, then retest the public website with Fixnx.
Who is affected
Affected versions
- 4.0.26-4.1.15
Fixed versions
- 4.1.16
How to fix it
Eventin – Event Calendar, Event Registration, Tickets & Booking (AI Powered) is affected by CVE-2026-13039, a authorization bypass issue in 4.0.26-4.1.15. Wordfence lists the official remediation as updating to version 4.1.16, or a newer patched version. Prioritize internet-facing WordPress sites, sites with public registration, customer portals, Elementor/page-builder surfaces, reservation or booking workflows, and admin workflows where the vulnerable feature is enabled. If immediate patching is not possible, disable the affected plugin or feature, restrict access, and monitor for exploitation until the update is installed.
- Inventory every WordPress site that has Eventin – Event Calendar, Event Registration, Tickets & Booking (AI Powered) installed, including production, staging, multisite, client, WooCommerce, marketplace, and booking environments.
- Confirm the installed Eventin – Event Calendar, Event Registration, Tickets & Booking (AI Powered) version and compare it with the affected range from the Wordfence advisory.
- Update Eventin – Event Calendar, Event Registration, Tickets & Booking (AI Powered) to version 4.1.16, or to a newer vendor-supported patched version from the official WordPress update channel.
- If the update cannot be applied immediately, disable Eventin – Event Calendar, Event Registration, Tickets & Booking (AI Powered) or the affected feature and restrict access with roles, authentication, WAF rules, or temporary route blocking.
- Review affected REST endpoints, AJAX actions, roles, capabilities, account changes, orders, bookings, payments, marketplace vendor actions, and admin actions for unauthorized activity.
- Rotate administrator sessions, API keys, webhook secrets, payment or integration tokens, and affected credentials if logs or content review suggest compromise.
- Clear WordPress, object, CDN, page-builder, security plugin, WooCommerce, and browser caches after patching so vulnerable assets or stored payloads are not served.
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Verify the fix
- Confirm the running Eventin – Event Calendar, Event Registration, Tickets & Booking (AI Powered) version is version 4.1.16 or newer, and record the patched version in the remediation ticket.
- Verify unauthenticated or low-privilege users can no longer trigger the affected action, endpoint, account, vendor, payment, booking, invoice, or settings change.
- Review web server, WordPress, security plugin, WAF, database, WooCommerce, and application logs for exploitation attempts before and after the fix.
- Retest normal visitor, subscriber, customer, vendor, editor, administrator, checkout, form, API, booking, reservation, invoice, or integration workflows to confirm expected behavior still works.
- Run a fresh Fixnx scan and document the public exposure state, patched version, log review, and any cleanup evidence.
Related categories
Trusted references
FAQ
What is affected by CVE-2026-13039?
Eventin – Event Calendar, Event Registration, Tickets & Booking (AI Powered) versions listed as affected should be reviewed: 4.0.26-4.1.15.
What should I fix first?
Start with internet-facing sites, admin panels, login flows, plugins, themes, modules, packages, and systems that process user-controlled input or sensitive data.
How do I confirm the fix worked?
Apply the patched version or mitigation, clear caches where relevant, retest the affected workflow, and run a new Fixnx scan to verify public website exposure signals.
How are Fixnx security risk categories chosen?
Fixnx keeps one canonical risk page and assigns only broad, relevant categories such as ecosystem, technology area, or vulnerability class.