CVE-2026-105989 Overview
CVE-2026-105989 affects the Accept PayPal Payments using Contact Form 7 WordPress plugin in versions before 4.0.7. The plugin exposes an AJAX action without performing authorization or request-validation checks. Unauthenticated attackers can forge the stored transaction status of records and write the plugin's status metadata onto arbitrary posts. The flaw is categorized as Missing Authorization [CWE-862] and carries a network attack vector with low attack complexity and no required privileges or user interaction.
Critical Impact
Unauthenticated remote attackers can tamper with PayPal transaction status records and inject plugin status metadata into arbitrary WordPress posts, undermining the integrity of payment records.
Affected Products
- Accept PayPal Payments using Contact Form 7 WordPress plugin versions before 4.0.7
- WordPress sites using Contact Form 7 with the vulnerable PayPal integration
- Any site relying on the plugin's AJAX transaction status handler
Discovery Timeline
- 2026-10-10 - CVE-2026-105989 published to the National Vulnerability Database (NVD)
- 2026-10-13 - Last updated in NVD database
Technical Details for CVE-2026-105989
Vulnerability Analysis
The vulnerability resides in one of the plugin's AJAX action handlers. The handler does not verify the capability of the requester, nor does it validate the authenticity of the inbound request through a nonce or similar token. As a result, any unauthenticated visitor can invoke the endpoint and manipulate post metadata that the plugin uses to track PayPal transaction state.
The impact centers on data integrity. Attackers can mark unpaid transactions as completed, revert completed transactions to pending, or write transaction status metadata onto posts that have no relationship to PayPal payments. Confidentiality and availability are not directly affected, but downstream workflows that trust the transaction status (order fulfillment, email receipts, access provisioning) can be subverted.
Root Cause
The root cause is Missing Authorization [CWE-862] on an AJAX endpoint. The handler is registered without a capability check (current_user_can()) and without a nonce verification (check_ajax_referer()). The endpoint also fails to validate that the targeted post identifier belongs to a legitimate PayPal transaction record.
Attack Vector
Exploitation requires only network access to the WordPress site. An attacker sends a crafted HTTP POST request to the WordPress admin-ajax.php endpoint, specifying the vulnerable action name and arbitrary post identifiers and status values. No authentication or user interaction is required. Technical details are documented in the WPScan Vulnerability Report.
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Indicators of Compromise
- Unexpected modifications to PayPal transaction status metadata on posts that were not previously associated with payments.
- Unauthenticated POST requests to admin-ajax.php referencing the plugin's AJAX action name.
- Discrepancies between PayPal merchant transaction logs and the plugin's recorded status values.
Detection Strategies
- Audit WordPress post metadata for the plugin's status keys applied to posts that are not of the expected transaction type.
- Review web server access logs for anonymous requests to /wp-admin/admin-ajax.php with the vulnerable action parameter.
- Compare order and transaction state against authoritative PayPal reports to flag forged completions.
Monitoring Recommendations
- Alert on bursts of POST requests to admin-ajax.php from a single source IP without an authenticated session cookie.
- Enable WordPress audit logging to capture metadata changes on posts outside normal editorial workflows.
- Forward WordPress and web server logs to a centralized SIEM for correlation with payment processor events.
How to Mitigate CVE-2026-105989
Immediate Actions Required
- Upgrade the Accept PayPal Payments using Contact Form 7 plugin to version 4.0.7 or later.
- Reconcile recent PayPal transaction records against merchant-side PayPal reports to identify forged status entries.
- Restrict unauthenticated access to admin-ajax.php where feasible using a web application firewall rule.
Patch Information
The vendor addressed the issue in version 4.0.7 of the Accept PayPal Payments using Contact Form 7 WordPress plugin. Site administrators should update through the WordPress plugin management console or via WP-CLI. Confirm the installed version after update and review the WPScan Vulnerability Report for additional guidance.
Workarounds
- Deactivate the plugin until the patched version can be installed if payment processing is not actively required.
- Deploy a WAF rule to block POST requests to admin-ajax.php that target the vulnerable action from unauthenticated sources.
- Enforce strict access controls on the WordPress admin surface via IP allowlisting or authentication proxies.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
