CVE-2006-0706 in Gastebuch
Summary
by MITRE
Cross-site scripting vulnerability in eintrag.php in Gästebuch (Gastebuch) before 1.3.3 allows remote attackers to inject arbitrary web script or HTML via the URL, which is used in the homepage parameter.
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Analysis
by VulDB Data Team • 11/11/2025
The vulnerability identified as CVE-2006-0706 represents a classic cross-site scripting flaw within the Gästebuch guestbook application, specifically affecting versions prior to 1.3.3. This security weakness resides in the eintrag.php script where user-supplied input from the URL parameter named homepage is not properly sanitized or validated before being rendered back to users. The vulnerability falls under the CWE-79 category of Cross-Site Scripting, which is one of the most prevalent and well-documented web application security flaws in the industry. The attack vector is particularly concerning as it allows remote attackers to execute malicious scripts in the context of the victim's browser without requiring any privileged access or complex exploitation techniques.
The technical implementation of this vulnerability stems from the application's failure to implement proper input validation and output encoding mechanisms. When a user submits a URL containing malicious script code within the homepage parameter, the application processes this input without adequate sanitization measures. The script code is then stored and subsequently displayed in the guestbook entries without proper HTML escaping or script context encoding. This creates an environment where attackers can inject malicious JavaScript code, HTML content, or other harmful payloads that execute within the victim's browser session. The vulnerability is particularly dangerous because it leverages the trust relationship between the web application and its users, allowing attackers to bypass normal security restrictions that would otherwise protect against such malicious activities.
The operational impact of this vulnerability extends beyond simple data theft or defacement. Attackers can leverage this XSS flaw to perform session hijacking, steal sensitive cookies, redirect users to malicious websites, or inject malicious content that could compromise the entire user base of the guestbook application. The vulnerability affects the integrity and confidentiality of user data, potentially leading to unauthorized access to personal information or system resources. From an attacker's perspective, this vulnerability provides a low-effort, high-impact method for compromising the application and its users, making it an attractive target for malicious actors. The attack can be executed through simple URL manipulation without requiring any specialized tools or deep technical knowledge, which significantly increases the attack surface and potential impact.
Mitigation strategies for this vulnerability should focus on implementing robust input validation and output encoding practices. The most effective approach involves sanitizing all user-supplied input, particularly URL parameters, before processing or storing them within the application. This includes implementing proper HTML escaping mechanisms that convert special characters into their safe representations before rendering content to users. The application should also implement Content Security Policy (CSP) headers to prevent unauthorized script execution and limit the sources from which scripts can be loaded. Additionally, regular security updates and patch management are essential to ensure that all known vulnerabilities are addressed promptly. The fix for this specific vulnerability would require updating the Gästebuch application to version 1.3.3 or later, where proper input sanitization mechanisms have been implemented to prevent the injection of malicious scripts through the homepage parameter. This vulnerability demonstrates the critical importance of input validation and output encoding in preventing cross-site scripting attacks, aligning with fundamental security principles outlined in various security frameworks and standards including those referenced in the ATT&CK framework under the web application attack patterns.