CVE-2002-0457 in BG Guestbook
Summary
by MITRE
Cross-site scripting vulnerability in signgbook.php for BG GuestBook 1.0 allows remote attackers to execute arbitrary Javascript via encoded tags such as <, >, and & in fields such as (1) name, (2) email, (3) AIM screen name, (4) website, (5) location, or (6) message.
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Analysis
by VulDB Data Team • 09/17/2025
This cross-site scripting vulnerability exists in the signgbook.php script of BG GuestBook version 1.0, representing a classic injection flaw that enables remote attackers to execute malicious javascript code within the context of victim browsers. The vulnerability stems from inadequate input validation and output encoding mechanisms within the guestbook application, specifically failing to properly sanitize user-supplied data before rendering it on web pages. The affected parameters include six distinct input fields: name, email, AIM screen name, website, location, and message, all of which accept encoded characters such as less than, greater than, and ampersand symbols that can be exploited to inject malicious payloads. This vulnerability directly maps to CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'), which is classified as a critical weakness in web application security. The attack vector allows adversaries to craft malicious input containing javascript code within the vulnerable fields, which when displayed on the guestbook page becomes executable within the browser context of other users who view the affected entries. The operational impact is significant as this vulnerability enables attackers to perform various malicious activities including session hijacking, defacement of the guestbook content, redirection to malicious websites, or even credential theft from users who may be authenticated within the same domain. According to ATT&CK framework, this vulnerability aligns with T1531: Establishing Persistence and T1566: Phishing, as it can be leveraged to create persistent malicious content and serve as a delivery mechanism for more sophisticated attacks. The vulnerability demonstrates poor secure coding practices where user input is directly incorporated into HTML output without proper sanitization or encoding, violating fundamental web security principles. The exploitation requires minimal technical skill as attackers can simply input malicious javascript within any of the six vulnerable fields, making this a particularly dangerous vulnerability for public-facing guestbook applications. Organizations using this software should immediately implement input validation and output encoding measures, including HTML entity encoding of all user-supplied content before rendering it on web pages, to prevent the execution of malicious scripts. The remediation strategy must also include comprehensive input filtering that removes or encodes potentially dangerous characters and implements proper content security policies to further mitigate the risk of cross-site scripting attacks.