CVE-2014-4650 in Python
Summary
by MITRE
The CGIHTTPServer module in Python 2.7.5 and 3.3.4 does not properly handle URLs in which URL encoding is used for path separators, which allows remote attackers to read script source code or conduct directory traversal attacks and execute unintended code via a crafted character sequence, as demonstrated by a %2f separator.
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Analysis
by VulDB Data Team • 01/01/2025
The vulnerability identified as CVE-2014-4650 resides within the CGIHTTPServer module of Python versions 2.7.5 and 3.3.4, representing a critical directory traversal flaw that exploits improper URL decoding mechanisms. This vulnerability specifically targets the handling of URL-encoded path separators where attackers can manipulate encoded forward slashes %2f to navigate directories beyond the intended scope. The flaw stems from the module's inadequate validation of URL-encoded sequences that should be properly normalized before path resolution occurs.
The technical implementation of this vulnerability exploits the fundamental mismatch between URL encoding standards and filesystem path handling within the Python HTTP server implementation. When a request contains URL-encoded path separators such as %2f, the CGIHTTPServer module fails to properly decode and normalize these sequences, allowing attackers to bypass directory restrictions and access files outside the intended web root directory. This improper handling creates a path traversal condition where malicious requests can traverse the filesystem hierarchy and potentially access sensitive files including script source code, configuration files, or other system resources that should remain protected.
The operational impact of CVE-2014-4650 extends beyond simple information disclosure to encompass full code execution capabilities within the context of the web server process. Attackers can leverage this vulnerability to read script source code, potentially exposing sensitive application logic, database credentials, or other confidential information. More critically, the vulnerability enables directory traversal attacks that can lead to arbitrary code execution, allowing malicious actors to inject and execute unauthorized commands on the affected system. This makes the vulnerability particularly dangerous in environments where the Python HTTP server is used for serving dynamic content or where the server process has elevated privileges.
Mitigation strategies for CVE-2014-4650 should focus on immediate patching of affected Python versions to the latest stable releases that contain proper URL normalization and path validation. Organizations should also implement web application firewalls or reverse proxies that can normalize URL-encoded sequences before they reach the vulnerable Python module. Additionally, system administrators should disable unnecessary HTTP server functionality and ensure that CGI scripts are properly sandboxed with restricted file access permissions. This vulnerability aligns with CWE-22 Directory Traversal and is categorized under ATT&CK technique T1059 for command and script injection, making it a significant concern for both defensive and offensive security operations.
The vulnerability demonstrates the critical importance of proper input validation and URL decoding in web server implementations, particularly when handling encoded sequences that could potentially alter the intended execution path of filesystem operations. Organizations using older Python versions should consider migrating to supported releases that include enhanced security measures for URL handling and path normalization to prevent exploitation of similar vulnerabilities in the future.