CVE-2006-0361 in Bit 5 Blog
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in addcomment.php in Bit 5 Blog 8.01 allows remote attackers to inject arbitrary web script or HTML via a javascript URI in an <a> tag in the comment parameter, which strips most tags but not <a>.
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Analysis
by VulDB Data Team • 07/29/2025
The vulnerability identified as CVE-2006-0361 represents a classic cross-site scripting flaw within the Bit 5 Blog 8.01 content management system that specifically targets the addcomment.php script. This security weakness arises from inadequate input validation and sanitization mechanisms that fail to properly filter malicious content submitted through the comment parameter. The vulnerability occurs when users submit comments containing specially crafted javascript URIs embedded within anchor tags, exploiting a processing gap in the HTML sanitization routine that selectively removes most tags while leaving anchor elements intact.
The technical implementation of this vulnerability stems from the application's flawed approach to HTML sanitization where the system strips most HTML tags from user input but maintains the <a> tag element, creating an exploitable vector for malicious script injection. When a remote attacker submits a comment containing a javascript URI within an anchor tag such as <a href="javascript:alert('xss')">click me</a>, the system processes this input without adequately validating or escaping the javascript portion of the URI. This processing gap allows the malicious script to execute within the context of other users' browsers when they view the affected comment, making it a persistent threat that can compromise user sessions and potentially exfiltrate sensitive information.
The operational impact of this vulnerability extends beyond simple script execution to encompass broader security implications for the affected blog platform and its users. Attackers can leverage this vulnerability to steal session cookies, redirect users to malicious websites, perform actions on behalf of authenticated users, or even establish persistent backdoors through more sophisticated attack vectors. The vulnerability affects the integrity of the blog's user interaction model and can undermine trust in the platform's security measures, potentially leading to reputational damage and regulatory compliance issues for organizations relying on the affected software. According to CWE classification, this represents a CWE-79: Improper Neutralization of Input During Web Page Generation, which is a fundamental weakness in web application security that enables various forms of injection attacks.
Mitigation strategies for this vulnerability should focus on comprehensive input validation and output encoding mechanisms that prevent the execution of malicious scripts regardless of the HTML elements present in user-submitted content. Organizations should implement strict HTML sanitization that removes or escapes all javascript protocols from anchor tags and other potentially dangerous HTML elements. The recommended approach includes implementing a whitelist-based filtering system that only allows safe HTML elements and attributes while thoroughly escaping or removing any javascript content. Additionally, the application should employ proper output encoding techniques such as HTML entity encoding for all user-generated content before rendering it on web pages. Security measures should also include regular security audits and code reviews to identify similar patterns in other parts of the application that might present similar vulnerabilities. From an ATT&CK framework perspective, this vulnerability maps to T1059.007: Command and Scripting Interpreter: JavaScript, representing a technique that attackers use to execute malicious code through web-based interfaces, and T1566.001: Impair Defenses: Disable or Modify Tools, as the vulnerability could be exploited to bypass security controls that rely on proper input validation.
The vulnerability demonstrates the critical importance of comprehensive security testing and the need for robust input validation mechanisms in web applications. It highlights how seemingly minor implementation gaps in HTML sanitization can create significant security risks that affect the entire user base of a web application. Organizations should prioritize security training for developers to understand the implications of improper input handling and implement automated security testing tools that can detect similar vulnerabilities during the development lifecycle. Regular security updates and patches are essential for maintaining protection against such vulnerabilities, particularly in legacy systems that may not receive ongoing security support from their vendors. The presence of this vulnerability in a widely used blogging platform underscores the necessity of maintaining up-to-date security practices and the importance of conducting thorough security assessments of all web applications to prevent exploitation of similar flaws that could compromise user data and system integrity.