CVE-2002-0730 in Guestbook
Summary
by MITRE
Cross-site scripting vulnerability in guestbook.pl for Philip Chinery s Guestbook 1.1 allows remote attackers to execute Javascript or HTML via fields such as (1) Name, (2) EMail, or (3) Homepage.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 09/14/2025
This cross-site scripting vulnerability exists in the guestbook.pl script version 1.1 developed by Philip Chinery, representing a critical security flaw that enables remote attackers to inject malicious client-side scripts into web applications. The vulnerability specifically affects input fields including Name, Email, and Homepage, which are commonly used in guestbook applications to collect user information. The flaw stems from inadequate input validation and output sanitization mechanisms within the script, allowing malicious actors to submit specially crafted payloads that get executed in the context of other users' browsers when they view the guestbook entries.
The technical implementation of this vulnerability aligns with CWE-79, which describes Cross-Site Scripting (XSS) flaws where untrusted data is improperly incorporated into web pages without proper validation or encoding. The vulnerability operates by bypassing the application's security controls that should sanitize user inputs before displaying them on the web page. When users enter JavaScript code or HTML tags into the vulnerable fields, the script fails to properly escape or filter these inputs, resulting in the malicious code being executed in the victim's browser context. This creates a persistent threat where every visitor to the guestbook page becomes a potential victim of the stored XSS attack.
The operational impact of this vulnerability extends beyond simple script execution, as it enables attackers to perform various malicious activities including session hijacking, credential theft, defacement of the guestbook content, and redirection to malicious websites. Attackers can exploit this vulnerability to steal cookies, modify guestbook entries, or even execute more sophisticated attacks such as phishing campaigns targeting other users of the same website. The persistent nature of stored XSS means that the malicious code remains active until the administrator removes the compromised entries, potentially affecting all users who access the vulnerable guestbook over an extended period.
Mitigation strategies for this vulnerability should focus on implementing comprehensive input validation and output encoding mechanisms to prevent malicious code injection. The recommended approach involves sanitizing all user inputs by removing or escaping special characters that could be interpreted as HTML or JavaScript tags. Implementing Content Security Policy (CSP) headers can provide additional protection by restricting the sources from which scripts can be loaded. Organizations should also consider using parameterized queries and proper HTML escaping functions when displaying user-generated content. This vulnerability demonstrates the importance of following secure coding practices as outlined in OWASP Top Ten and ATT&CK framework techniques related to web application vulnerabilities, specifically targeting the execution of malicious code through XSS vectors and the compromise of user sessions through persistent script injection attacks.