CVE-2006-5050 in BusyBox
Summary
by MITRE
Directory traversal vulnerability in httpd in Rob Landley BusyBox allows remote attackers to read arbitrary files via URL-encoded "%2e%2e/" sequences in the URI.
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Analysis
by VulDB Data Team • 04/23/2026
The vulnerability identified as CVE-2006-5050 represents a classic directory traversal flaw within the httpd component of Rob Landley BusyBox, a widely deployed embedded web server solution. This security weakness enables remote attackers to access files outside the intended web root directory by exploiting URL encoding techniques that manipulate directory navigation sequences. The vulnerability specifically leverages the encoding of dot-dot sequences as "%2e%2e/" which when processed by the web server can bypass normal directory access controls and permit unauthorized file retrieval.
This directory traversal vulnerability stems from inadequate input validation within the httpd implementation, where URI components containing encoded path traversal sequences are not properly sanitized before being processed. The flaw allows attackers to construct malicious URLs that, when decoded and interpreted by the web server, can navigate to arbitrary directories and access sensitive files that should remain protected from remote access. The vulnerability exists in the core file path resolution logic where the web server fails to adequately validate or normalize URI components that contain encoded directory traversal sequences.
The operational impact of this vulnerability is significant as it can potentially expose sensitive system files, configuration data, and user information to remote attackers without authentication. Attackers can leverage this weakness to access system files such as password files, configuration databases, application source code, and other confidential data stored on the server. The vulnerability affects systems running BusyBox httpd implementations, which are commonly found in embedded devices, network appliances, and lightweight server environments where security controls may be minimal or absent.
The technical nature of this vulnerability aligns with CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. This weakness allows attackers to access files and directories stored outside the web root folder by manipulating variables that reference files with "dot-dot-slash" (../) sequences and their variations. The specific implementation in BusyBox httpd demonstrates how embedded web servers often lack the robust input validation controls found in enterprise-grade web applications, making them particularly susceptible to such attacks.
Mitigation strategies for this vulnerability include implementing proper input validation and normalization of URI components to prevent the processing of encoded directory traversal sequences. System administrators should ensure that all web server implementations properly sanitize user input and validate file access requests against a predefined whitelist of allowed paths. Additionally, updating to newer versions of BusyBox that address this vulnerability is crucial, as the original implementation lacks proper security controls to prevent such attacks. Network segmentation and access control measures can also help limit the potential impact of successful exploitation attempts, while monitoring for suspicious URI patterns can aid in detecting attempted directory traversal attacks. The vulnerability also highlights the importance of following security best practices such as the principle of least privilege and implementing proper input validation controls to prevent unauthorized access to system resources.