CVE-2002-0503 in Nfuse
Summary
by MITRE
Directory traversal vulnerability in boilerplate.asp for Citrix NFuse 1.5 allows remote authenticated users to read arbitrary files via a .. (dot dot) in the NFuse_Template parameter.
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Analysis
by VulDB Data Team • 09/16/2025
The vulnerability described in CVE-2002-0503 represents a classic directory traversal flaw that existed in Citrix NFuse 1.5's boilerplate.asp component. This issue stems from inadequate input validation within the web application's parameter handling mechanism, specifically affecting the NFuse_Template parameter. The flaw allows authenticated remote attackers to manipulate file path references through the use of directory traversal sequences such as .. which are commonly used to navigate up directory levels in file systems. The vulnerability is particularly concerning because it operates within a web application context where users must be authenticated to exploit the issue, yet the authentication requirement does not prevent the exploitation of the underlying path traversal mechanism.
This directory traversal vulnerability directly maps to CWE-22, which defines the weakness of improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal. The flaw enables attackers to access files outside the intended directory structure, potentially leading to unauthorized data access, information disclosure, and system compromise. The specific exploitation occurs when the application processes the NFuse_Template parameter without proper sanitization or validation of directory traversal sequences, allowing malicious input to be interpreted as legitimate file path navigation instructions. The attack vector requires an authenticated user context, which reduces the attack surface compared to unauthenticated vulnerabilities but still poses significant risks within trusted network environments.
The operational impact of this vulnerability extends beyond simple file reading capabilities and can potentially expose sensitive system information, configuration files, and application data. An authenticated attacker could leverage this flaw to access system files, application source code, database connection strings, and other sensitive information that could be used for further exploitation. The vulnerability's exploitation requires minimal technical skill and can be automated, making it particularly dangerous in environments where multiple users have legitimate access to the NFuse application. This type of vulnerability often serves as a stepping stone for more sophisticated attacks, as the leaked information can reveal system architecture, application logic, and potential weak points in the overall security posture. The attack can be executed through simple HTTP requests that manipulate the NFuse_Template parameter, making it difficult to detect and prevent without proper input validation controls.
Mitigation strategies for this vulnerability should focus on implementing robust input validation and sanitization mechanisms within the application layer. The most effective approach involves proper parameter validation that rejects or removes directory traversal sequences such as .. from user input before processing. This aligns with the principle of least privilege and input sanitization practices recommended by security frameworks and standards. Organizations should implement proper access controls and ensure that the application operates with minimal required privileges to prevent unauthorized file access even if the vulnerability is exploited. The fix typically involves modifying the boilerplate.asp script to validate and sanitize all input parameters, particularly those used in file path constructions. Additionally, implementing web application firewalls and security monitoring solutions can help detect and prevent exploitation attempts. This vulnerability also highlights the importance of regular security assessments and code reviews to identify and remediate similar issues in legacy applications that may not have been designed with modern security practices in mind. The remediation process should include comprehensive testing to ensure that the fix does not introduce regressions in application functionality while maintaining the security posture against similar traversal attacks.