CVE-2008-5626 in XM Easy Personal FTP Server
Summary
by MITRE
XM Easy Personal FTP Server 5.6.0 allows remote authenticated users to cause a denial of service via a crafted argument to the NLST command, as demonstrated by a -1 argument.
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Analysis
by VulDB Data Team • 05/24/2025
The vulnerability identified as CVE-2008-5626 affects XM Easy Personal FTP Server version 5.6.0 and represents a denial of service flaw that can be exploited by remote authenticated users. This vulnerability specifically targets the NLST command implementation within the FTP server software, demonstrating how improper input validation can lead to system instability and service disruption. The flaw manifests when a malicious user sends a crafted argument to the NLST command, with the demonstration showing the use of a -1 argument that triggers the vulnerability.
The technical root cause of this vulnerability lies in the insufficient validation of user-supplied arguments within the NLST command handler. When the server receives the malformed -1 argument, it fails to properly sanitize or validate the input before processing it, leading to a condition where the server's processing logic becomes unstable. This type of vulnerability falls under the category of improper input validation as classified by CWE-20, which is a fundamental weakness in software design that allows malicious inputs to disrupt normal program execution. The vulnerability demonstrates how a simple integer argument can cause cascading failures within the server's command processing mechanism.
The operational impact of this vulnerability extends beyond simple service disruption as it represents a potential vector for more sophisticated attacks within a broader exploitation framework. Remote authenticated users who can establish connections to the FTP server can leverage this flaw to repeatedly cause the service to become unresponsive or crash entirely. This denial of service condition can significantly impact business operations by making the FTP server unavailable to legitimate users, potentially affecting file transfer operations, backup processes, and other critical functions that depend on the server's availability. The vulnerability also aligns with ATT&CK technique T1499.004, which covers network denial of service attacks through exploitation of server-side vulnerabilities.
Mitigation strategies for this vulnerability should focus on implementing proper input validation and sanitization within the NLST command handler. System administrators should immediately update to patched versions of XM Easy Personal FTP Server where available, as this vulnerability represents a clear security weakness that can be exploited without significant technical expertise. Additionally, implementing network-level protections such as rate limiting and connection monitoring can help detect and prevent exploitation attempts. The vulnerability also highlights the importance of proper error handling and input validation in server-side applications, aligning with security best practices outlined in frameworks such as OWASP Top Ten and NIST guidelines for secure coding practices. Organizations should also consider implementing intrusion detection systems that can identify suspicious FTP command sequences and monitor for patterns consistent with this type of exploitation attempt.