CVE-2001-0826 in CesarFTP
Summary
by MITRE
Buffer overflows in CesarFTPD 0.98b allows remote attackers to execute arbitrary commands via long arguments to (1) HELP, (2) USER, (3) PASS, (4) PORT, (5) DELE, (6) REST, (7) RMD, or (8) MKD.
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Analysis
by VulDB Data Team • 10/04/2025
The vulnerability identified as CVE-2001-0826 represents a critical buffer overflow flaw in CesarFTPD version 0.98b, a lightweight ftp server implementation that was widely used in early internet infrastructure. This vulnerability resides in the server's handling of user input through multiple command interfaces, specifically targeting the HELP, USER, PASS, PORT, DELE, REST, RMD, and MKD commands. The flaw stems from inadequate input validation and bounds checking within the ftp server's command processing routines, creating exploitable conditions where malformed input can overwrite adjacent memory regions.
The technical nature of this vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The buffer overflow occurs when remote attackers send specially crafted arguments exceeding the allocated buffer size to any of the eight vulnerable commands. This allows malicious input to overwrite the stack frame, potentially corrupting return addresses and enabling arbitrary code execution with the privileges of the ftpd process. The vulnerability is particularly dangerous because it affects core authentication and file management commands, providing attackers with extensive control over the target system.
From an operational perspective, this vulnerability presents a severe risk to systems running the affected ftp server version, as it enables remote command execution without requiring authentication. Attackers can leverage this flaw to gain full system control, potentially leading to data breaches, system compromise, and further lateral movement within networks. The impact extends beyond immediate system compromise, as the vulnerability can be exploited by automated scanning tools and represents a significant weakness in the server's security architecture. The widespread use of CesarFTPD in early internet deployments made this vulnerability particularly dangerous, as it could affect numerous systems simultaneously.
Security mitigation strategies for this vulnerability must address both immediate remediation and long-term architectural improvements. The primary solution involves upgrading to a patched version of CesarFTPD or migrating to a more secure ftp server implementation such as vsftpd or ProFTPD. Organizations should implement network segmentation and access controls to limit exposure to this vulnerability, while also deploying intrusion detection systems to monitor for exploitation attempts. The vulnerability demonstrates the importance of input validation and bounds checking in network services, aligning with ATT&CK technique T1059.007 for command and scripting interpreter and T1210 for exploitation of remote services. Additionally, this vulnerability highlights the necessity of regular security assessments and patch management programs to prevent exploitation of known vulnerabilities in legacy systems.