Overview
This article details a stored Cross-Site Scripting (XSS) vulnerability discovered in DzzOffice version 2.3.x, identified as CVE-2025-63693. The vulnerability resides within the comment editing template, specifically dzz/comment/template/edit_form.htm, and stems from insufficient security escaping of user-controllable data. This allows an attacker with low privileges to inject arbitrary JavaScript code, which is then executed when a victim opens the comment editing popup.
Technical Details
The core issue lies in the lack of proper output encoding within the edit_form.htm template. User-provided data, intended for comment content or request parameters, is not adequately sanitized before being rendered in the HTML context, and particularly within JavaScript strings used by the page. An attacker can craft a malicious comment containing JavaScript code embedded within HTML tags or directly within JavaScript code blocks. When a user attempts to edit this comment, the injected JavaScript is executed within their browser session, potentially leading to account compromise, data theft, or other malicious activities.
For instance, a payload like <script>alert('XSS')</script> or ");alert('XSS');//, placed within a comment’s text, can be persistently stored and executed when the comment is edited.
<!-- Vulnerable Code Snippet (Illustrative) -->
<input type="text" value="{$comment.content}"> <!-- Unsanitized Input -->
<script>
var comment_text = "{$comment.content}"; // Unsanitized Input
// ... other JavaScript code using comment_text
</script>
CVSS Analysis
Currently, the CVSS score for CVE-2025-63693 is marked as N/A. However, given the nature of the vulnerability (stored XSS) and its potential impact, it is likely to be rated as Medium to High severity once a formal CVSS score is assigned. A stored XSS vulnerability allows attackers to permanently compromise legitimate users. A user interaction (editing the comment) is required to trigger the vulnerability.
Possible Impact
Successful exploitation of this vulnerability can lead to several serious consequences:
- Account Compromise: An attacker can steal a victim’s session cookies, allowing them to impersonate the victim and gain unauthorized access to their account.
- Data Theft: Sensitive data displayed within the DzzOffice interface can be accessed and exfiltrated by the attacker.
- Malware Distribution: The attacker could inject malicious scripts to redirect users to phishing sites or install malware on their systems.
- Defacement: The attacker could modify the content of the DzzOffice application, potentially defacing the website.
Mitigation or Patch Steps
The primary mitigation strategy is to upgrade to a patched version of DzzOffice that addresses the vulnerability. Until a patch is available, the following temporary measures can be considered:
- Input Validation: Implement robust input validation on the server-side to sanitize user-provided comment content, filtering out potentially malicious HTML tags and JavaScript code.
- Output Encoding: Ensure that all user-controllable data displayed within the
edit_form.htmtemplate is properly encoded using appropriate escaping functions (e.g., HTML encoding for HTML contexts, JavaScript encoding for JavaScript contexts) to prevent XSS attacks. - Web Application Firewall (WAF): Deploy a WAF configured with rules to detect and block XSS attacks.
