CVE-2003-1546 in Guestbook
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in gbook.php in Filebased guestbook 1.1.3 allows remote attackers to inject arbitrary web script or HTML via the comment section.
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Analysis
by VulDB Data Team • 07/13/2025
The vulnerability identified as CVE-2003-1546 represents a classic cross-site scripting flaw within the Filebased guestbook 1.1.3 application's gbook.php component. This security weakness resides in the application's handling of user input within the comment section, creating an exploitable condition that enables remote attackers to inject malicious web scripts or HTML code. The vulnerability manifests when user-supplied data is directly incorporated into web page responses without proper sanitization or output encoding mechanisms, allowing attackers to manipulate the application's behavior and potentially compromise user sessions or execute unauthorized actions.
The technical implementation of this XSS vulnerability stems from insufficient input validation and output encoding practices within the guestbook application. When users submit comments through the gbook.php interface, the application fails to properly sanitize the input data before rendering it back to other users browsing the guestbook. This omission creates a pathway for attackers to embed malicious JavaScript code or HTML elements within the comment field that will execute in the context of other users' browsers when they view the guestbook entries. The vulnerability specifically targets the comment section functionality, making it particularly dangerous as guestbook applications typically serve as public-facing interfaces where multiple users can observe submitted content.
The operational impact of this vulnerability extends beyond simple script injection, potentially enabling attackers to perform session hijacking, deface the guestbook interface, or redirect users to malicious websites. An attacker could craft a comment containing JavaScript that steals session cookies, redirects victims to phishing sites, or modifies the guestbook's appearance to display unwanted content. This type of vulnerability can significantly compromise user trust in the application and potentially lead to broader security breaches if the guestbook is integrated with other systems or if users inadvertently execute malicious code through the injected scripts. The vulnerability affects all users who view the affected guestbook entries, making it particularly dangerous in environments where guestbooks serve as public interfaces for community interaction.
Security professionals should address this vulnerability through comprehensive input sanitization and output encoding measures. The recommended approach involves implementing strict validation of all user input within the comment section, ensuring that any potentially malicious content is either rejected or properly escaped before being rendered in web responses. This remediation strategy aligns with established security practices and addresses the fundamental flaw identified in the vulnerability. Organizations should also consider implementing content security policies and adopting secure coding practices that prevent similar issues in future development cycles. The vulnerability maps to CWE-79 which specifically addresses cross-site scripting flaws, and aligns with ATT&CK technique T1566 related to spearphishing attachments and links, as attackers could leverage this vulnerability to deliver malicious payloads through seemingly legitimate guestbook comments. Proper security testing including dynamic application security testing and static code analysis should be employed to identify and remediate similar vulnerabilities across the application stack.