CVE-2014-4877 in wget
Summary
by MITRE
Absolute path traversal vulnerability in GNU Wget before 1.16, when recursion is enabled, allows remote FTP servers to write to arbitrary files, and consequently execute arbitrary code, via a LIST response that references the same filename within two entries, one of which indicates that the filename is for a symlink.
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Analysis
by VulDB Data Team • 04/24/2025
The CVE-2014-4877 vulnerability represents a critical absolute path traversal flaw in GNU Wget versions prior to 1.16 that specifically manifests when recursive download functionality is enabled. This vulnerability stems from improper handling of FTP server responses during recursive directory traversal operations, creating a dangerous condition where remote attackers can manipulate file system operations through crafted LIST responses. The flaw occurs when the FTP server sends a directory listing containing multiple entries for the same filename, with one entry indicating the file is a symbolic link. This creates a scenario where wget's file system traversal logic can be manipulated to write to arbitrary locations on the target system, bypassing normal path validation mechanisms.
The technical implementation of this vulnerability exploits the way wget processes FTP directory listings during recursive operations. When wget encounters a directory listing with duplicate filenames, it fails to properly validate whether the file path is being manipulated through symbolic link references. The vulnerability specifically leverages the fact that wget does not adequately check for or handle cases where the same filename appears in multiple entries within an FTP LIST response, one of which indicates a symlink. This creates a race condition or path manipulation opportunity where wget may follow the symlink path and write data to locations outside the intended download directory. The flaw is particularly dangerous because it can be exploited without authentication, allowing remote attackers to write files to arbitrary locations on the victim system, potentially leading to privilege escalation or code execution.
The operational impact of CVE-2014-4877 extends beyond simple file system manipulation to potentially enable complete system compromise. Attackers can leverage this vulnerability to overwrite critical system files, install backdoors, or execute arbitrary code with the privileges of the user running wget. The vulnerability affects systems that use wget for downloading files from untrusted FTP sources, particularly those that enable recursive downloading. This includes automated download scripts, content management systems, and any application that relies on wget for file retrieval. The risk is compounded when wget is used in automated environments or with elevated privileges, as the attacker can potentially escalate privileges and gain full system control. According to CWE classification, this vulnerability maps to CWE-22 Path Traversal, which is a well-known weakness in input validation that allows attackers to access files outside the intended directory.
Mitigation strategies for CVE-2014-4877 primarily focus on upgrading to GNU Wget version 1.16 or later, which contains the necessary patches to properly handle FTP directory listings and prevent path traversal attacks. Organizations should also implement network segmentation and access controls to limit exposure to untrusted FTP servers. Additional protective measures include disabling recursive downloads when connecting to untrusted FTP sources, implementing network monitoring to detect suspicious FTP activity, and conducting regular security assessments of systems that use wget. The vulnerability demonstrates the importance of proper input validation in file system operations and highlights the need for robust path handling in network utilities. From an ATT&CK perspective, this vulnerability relates to T1059 Command and Scripting Interpreter and T1078 Valid Accounts, as it can lead to command execution and privilege escalation. System administrators should also consider implementing application whitelisting policies and regularly updating all network utilities to prevent exploitation of similar vulnerabilities in other software components.