CVE-2003-0558 in LeapFTP
Summary
by MITRE
Buffer overflow in LeapFTP 2.7.3.600 allows remote FTP servers to execute arbitrary code via a long IP address response to a PASV request.
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Analysis
by VulDB Data Team • 08/12/2025
The vulnerability identified as CVE-2003-0558 represents a critical buffer overflow flaw within LeapFTP version 2.7.3.600 that specifically targets the handling of IP address responses during FTP protocol operations. This vulnerability occurs when the client processes a PASV (Passive) command response from an FTP server, where the server sends back a formatted IP address string that exceeds the allocated buffer space in the client application. The flaw stems from inadequate input validation and bounds checking within the FTP client's response parsing mechanism, creating a scenario where malicious FTP servers can craft specially crafted responses that trigger memory corruption.
The technical execution of this vulnerability follows a well-established pattern that aligns with CWE-121, which categorizes buffer overflow conditions as a fundamental weakness in software design. When LeapFTP receives a PASV response containing an excessively long IP address field, the application fails to properly validate the length of the incoming data before copying it into a fixed-size buffer. This results in memory overwrite conditions that can potentially be exploited to redirect program execution flow. The attack vector is particularly concerning because it requires no local privileges or user interaction, making it a remote code execution vulnerability that can be exploited by any malicious FTP server that can intercept or spoof network traffic.
From an operational impact perspective, this vulnerability poses significant risks to systems that rely on LeapFTP for file transfer operations, particularly in environments where network traffic is not properly secured or monitored. The remote code execution capability means that attackers could gain full control over affected systems, potentially leading to data breaches, system compromise, and further lateral movement within network environments. The vulnerability affects the core functionality of the FTP client, making it a critical issue that could disrupt business operations while simultaneously providing attackers with a potent exploitation vector. Network administrators and security teams would need to urgently address this issue as it represents a serious threat to the integrity and confidentiality of systems using vulnerable versions of LeapFTP.
Mitigation strategies for CVE-2003-0558 should include immediate patching of LeapFTP installations to versions that properly validate input lengths and implement proper buffer management techniques. Organizations should also implement network segmentation and monitoring to detect unusual FTP traffic patterns that might indicate exploitation attempts. The vulnerability demonstrates the importance of implementing proper bounds checking and input validation as recommended by the software security principles outlined in the ATT&CK framework under the technique of "Exploitation for Code Execution". Additionally, network security controls such as firewalls and intrusion detection systems should be configured to monitor and restrict FTP traffic where possible, as this vulnerability could be leveraged as part of broader attack campaigns targeting network infrastructure. Organizations should also consider migrating to more secure and actively maintained FTP clients that follow modern security practices and have robust input validation mechanisms to prevent similar buffer overflow conditions from occurring in the future.