CVE-2026-84906 Overview
CVE-2026-84906 affects the Eventin WordPress plugin in versions before 4.1.24. The plugin fails to verify that a completed payment corresponds to the order it is applied to. The confirmation logic checks only that the payment gateway reports the transaction as successful, ignoring the transaction amount, currency, and order identifier. Unauthenticated visitors can mark unpaid orders of any value as paid by replaying the transaction reference of a single genuine low-value payment. The flaw is classified under [CWE-345] (Insufficient Verification of Data Authenticity) and represents a business logic error in payment reconciliation.
Critical Impact
Unauthenticated attackers can complete arbitrary-value event orders on affected sites by replaying a single low-cost payment transaction, resulting in revenue loss and fraudulent ticket issuance.
Affected Products
- Eventin WordPress plugin versions prior to 4.1.24
- WordPress sites using Eventin for paid event registration
- Deployments relying on Eventin's built-in payment gateway integration
Discovery Timeline
- 2026-09-16 - CVE-2026-84906 published to the National Vulnerability Database (NVD)
- 2026-09-16 - Last updated in NVD database
Technical Details for CVE-2026-84906
Vulnerability Analysis
The vulnerability resides in Eventin's payment confirmation workflow. When a payment gateway callback reports a successful transaction, the plugin marks the associated order as paid without cross-checking the transaction identifier against the order's expected amount, currency, or unique order reference.
Because the check is limited to the boolean success state returned by the gateway, any valid transaction reference can satisfy the condition. An attacker who has legitimately completed a low-value purchase on the target site can reuse that transaction reference to settle unrelated, higher-value orders. The vulnerability is network-reachable and requires no authentication or user interaction.
Root Cause
The root cause is insufficient verification of data authenticity in the payment reconciliation logic. The plugin trusts the transaction success signal in isolation. It does not bind the transaction to the specific order through validation of the amount, currency, gateway-side order metadata, or a one-time-use property on the transaction reference.
Attack Vector
An unauthenticated attacker first completes one legitimate low-value payment against the target site to obtain a valid gateway transaction reference. The attacker then submits that same transaction reference during the confirmation step of other, higher-value orders. The plugin queries the gateway, receives a successful status for the replayed reference, and marks the target orders as paid. The attack requires only HTTP access to the site's payment confirmation endpoint. Refer to the WPScan Vulnerability Report for additional technical details.
Detection Methods for CVE-2026-84906
Indicators of Compromise
- Multiple Eventin orders in the WordPress database sharing the same gateway transaction ID or reference.
- Orders marked as completed or paid where the recorded transaction amount does not match the order total.
- Repeated payment confirmation requests from the same IP address referencing different order_id values.
Detection Strategies
- Query the Eventin orders table for duplicate transaction identifiers across distinct orders and flag any matches.
- Reconcile paid orders against the payment gateway's transaction log and alert on any order whose amount or currency does not match the gateway record.
- Monitor web server access logs for anomalous request patterns hitting Eventin's payment confirmation endpoints from unauthenticated sessions.
Monitoring Recommendations
- Enable verbose logging on the payment gateway integration and forward events to a centralized log store for correlation.
- Alert on transaction reference reuse within a defined time window across the WordPress order pipeline.
- Review event ticket issuance reports against gateway settlement reports on a daily cadence during triage.
How to Mitigate CVE-2026-84906
Immediate Actions Required
- Upgrade the Eventin plugin to version 4.1.24 or later on all WordPress installations.
- Audit existing orders for duplicate transaction references and reverse fraudulent ticket issuance.
- Reconcile recent gateway settlements against WordPress order records to identify prior exploitation.
Patch Information
The vendor addressed the issue in Eventin version 4.1.24. Site administrators should update through the WordPress plugin manager or by deploying the updated plugin package. See the WPScan Vulnerability Report for advisory details.
Workarounds
- Disable the Eventin plugin until the patched version can be deployed if paid events are actively offered.
- Temporarily switch paid events to a manual approval workflow so administrators verify each transaction against gateway records before issuing tickets.
- Restrict access to Eventin payment endpoints using a web application firewall rule that enforces per-transaction uniqueness on submitted references.
# Update Eventin via WP-CLI to the patched release
wp plugin update wp-event-solution --version=4.1.24
wp plugin list | grep wp-event-solution
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.