CVE-2006-5728 in XM Easy Personal FTP Server
Summary
by MITRE
XM Easy Personal FTP Server 5.2.1 and earlier allows remote authenticated users to cause a denial of service via a long argument to the NLST command, possibly involving the -al flags.
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Analysis
by VulDB Data Team • 04/26/2026
The vulnerability identified as CVE-2006-5728 affects XM Easy Personal FTP Server version 5.2.1 and earlier, representing a denial of service weakness that can be exploited by authenticated remote attackers. This flaw specifically targets the NLST command implementation within the FTP server software, which is used to list directory contents. The vulnerability arises when a malicious user submits a particularly long argument to the NLST command, potentially combined with the -al flags that display detailed directory information including file permissions and ownership details.
The technical mechanism behind this vulnerability involves improper input validation and handling within the FTP server's command processing logic. When the NLST command receives an excessively long argument, the server fails to properly sanitize or limit the input length, leading to a buffer overflow condition or memory corruption scenario. This type of flaw falls under CWE-121, which categorizes buffer overflow conditions that can result in denial of service or potentially more severe consequences. The implementation lacks adequate bounds checking mechanisms to prevent excessive data from being processed by the server's internal parsing functions, causing the application to crash or become unresponsive.
From an operational impact perspective, this vulnerability allows authenticated attackers to disrupt the FTP service without requiring elevated privileges or specialized tools. The denial of service effect manifests as the server becoming unresponsive or crashing entirely, preventing legitimate users from accessing their files through the FTP interface. This vulnerability is particularly concerning because it requires only authentication credentials to exploit, meaning that any authorized user could potentially trigger the service disruption. The impact extends beyond simple service interruption as it can affect business operations, data accessibility, and overall system availability for legitimate users who depend on the FTP service for file transfers and management.
The exploitation of this vulnerability aligns with ATT&CK technique T1499.004, which covers network denial of service attacks through service interruption. Attackers can leverage this weakness to create sustained disruptions to the FTP service, potentially causing operational downtime that affects productivity and user satisfaction. The vulnerability also represents a failure in input validation that could be addressed through proper bounds checking and memory management practices. Organizations should implement immediate mitigations including applying the vendor-provided patch, implementing input length restrictions, and monitoring for suspicious command usage patterns. Additionally, network segmentation and access controls can help limit the potential impact of such vulnerabilities by restricting unauthorized access to the FTP service and reducing the attack surface available to malicious actors.