CVE-2003-1327 in wu-ftpd
Summary
by MITRE
Buffer overflow in the SockPrintf function in wu-ftpd 2.6.2 and earlier, when compiled with MAIL_ADMIN option enabled on a system that supports very long pathnames, might allow remote anonymous users to execute arbitrary code by uploading a file with a long pathname, which triggers the overflow when wu-ftpd constructs a notification message to the administrator.
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Analysis
by VulDB Data Team • 07/14/2025
The vulnerability described in CVE-2003-1327 represents a critical buffer overflow flaw within the wu-ftpd file transfer protocol server version 2.6.2 and earlier implementations. This security weakness specifically manifests within the SockPrintf function when the server is compiled with the MAIL_ADMIN option enabled, creating a scenario where remote anonymous users can exploit the system through carefully crafted file uploads. The flaw leverages the combination of long pathname handling and administrative notification mechanisms to create a remote code execution vector that has significant implications for system security.
The technical implementation of this vulnerability stems from improper buffer management within the SockPrintf function, which is responsible for constructing notification messages sent to system administrators when certain events occur. When the MAIL_ADMIN option is enabled, the ftpd server generates administrative messages that include information about uploaded files, including their pathnames. The buffer allocated for these messages does not properly validate the length of the pathname data, particularly when dealing with very long pathnames that exceed the allocated buffer space. This inadequate bounds checking creates a classic buffer overflow condition that can be triggered by uploading files with excessively long pathnames, causing the overflow to overwrite adjacent memory regions.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it provides remote attackers with the capability to execute arbitrary code on the affected system with the privileges of the ftpd process. This remote code execution vulnerability allows attackers to gain unauthorized access to the system, potentially leading to complete system compromise and persistent access. The attack vector specifically targets anonymous users, making it particularly dangerous as it does not require authentication credentials to exploit. The vulnerability affects systems where the wu-ftpd server is compiled with MAIL_ADMIN support and where the filesystem supports very long pathnames, creating a specific but significant attack surface.
The exploitability of this vulnerability is enhanced by the fact that it requires no authentication, making it particularly dangerous in publicly accessible ftpd installations. Attackers can simply connect anonymously and upload files with pathnames that exceed the buffer limits, triggering the overflow condition. This type of vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and represents a classic example of improper input validation in network services. The attack follows patterns consistent with the attack technique described in the MITRE ATT&CK framework under T1059.007 for command and script injection, as successful exploitation would allow arbitrary command execution.
Mitigation strategies for this vulnerability require immediate patching of affected wu-ftpd installations to versions that address the buffer overflow in the SockPrintf function. System administrators should disable the MAIL_ADMIN option if it is not strictly required for operational purposes, as this removes the vulnerable code path entirely. Additionally, implementing network segmentation and access controls to limit anonymous ftp access can reduce the attack surface. Regular security audits should verify that ftpd installations are running patched versions and that unnecessary administrative notification features are disabled. The vulnerability highlights the importance of proper buffer management and input validation in network services, particularly those handling user-supplied data in critical system functions.