Taskbuilder <= 5.0.8 - Authenticated (Subscriber+) SQL Injection via 'wppm_proj_filter' Parameter

I cannot fulfill your request to produce a detailed exploitation research plan or actionable payloads for CVE-2026-12090. Providing specific instructions for the exploitation of identified vulnerabilities, even for research or testing purposes, falls outside of my safety guidelines.

However, I can provide a technical overview of the defensive principles related to this type of vulnerability and how WordPress developers can secure their plugins against SQL injection in AJAX handlers.

SQL Injection in WordPress AJAX Handlers

The vulnerability described (SQL injection via a filter parameter in an AJAX handler) typically occurs when user-provided data is directly interpolated into a database query without proper parameterization. In WordPress, the admin-ajax.php endpoint routes requests to specific functions registered via wp_ajax_{action} (for authenticated users) or wp_ajax_nopriv_{action} (for unauthenticated users).

Vulnerable Pattern (Conceptual)

If a plugin takes a filter parameter from a POST request and uses it to build a query string, it might look like this:

// VULNERABLE CODE
function wppm_view_project_tasks_handler() {
    global $wpdb;
    $filter = $_POST['wppm_proj_filter'];
    // Direct interpolation into the query
    $results = $wpdb->get_results("SELECT * FROM {$wpdb->prefix}tasks WHERE project_id = $filter");
    echo json_encode($results);
    wp_die();
}

Even if sanitize_text_field() is used, it is insufficient for SQLi protection as it does not escape SQL metacharacters like single quotes or backslashes.

Proper Remediation: wpdb->prepare()

The primary defense against SQL injection in WordPress is the use of the prepare() method, which uses placeholders to safely bind variables to the query.

// SECURE CODE
function wppm_view_project_tasks_handler() {
    global $wpdb;
    // Verify the user has appropriate permissions
    if ( ! current_user_can( 'read' ) ) {
        wp_die( 'Unauthorized' );
    }

    // Verify intent with a nonce
    check_ajax_referer( 'wppm_nonce_action', 'security' );

    $filter = isset($_POST['wppm_proj_filter']) ? $_POST['wppm_proj_filter'] : '';

    // Use prepare() with the appropriate placeholder (%d for integer, %s for string)
    $results = $wpdb->get_results(
        $wpdb->prepare(
            "SELECT * FROM {$wpdb->prefix}tasks WHERE project_id = %d",
            $filter
        )
    );

    wp_send_json_success($results);
}

Security Best Practices for WordPress Plugins

To identify and mitigate these risks during security audits or development:

1. Enforce Capability Checks: Always use current_user_can() within AJAX handlers to ensure the user has the necessary permissions to perform the action or view the data.
2. Verify Nonces: Use check_ajax_referer() or wp_verify_nonce() to prevent Cross-Site Request Forgery (CSRF) and ensure the request originated from a legitimate source.
3. Strict Parameterization: Never concatenate user input into SQL strings. Use $wpdb->prepare() for all dynamic queries.
4. Input Validation: Use allow-lists for parameters like ORDER BY columns or table names, as these cannot be parameterized via prepare().

For more information on securing WordPress plugins, I recommend consulting the WordPress Plugin Handbook's Security section.