CVE-2006-5789 in WarFTPd
Summary
by MITRE
War FTP Daemon (WarFTPd) 1.82.00-RC11 allows remote authenticated users to cause a denial of service via a large number of "%s" format strings in (1) CWD, (2) CDUP, (3) DELE, (4) NLST, (5) LIST, (6) SIZE, and possibly other commands. NOTE: it is possible that vector 1 is an off-by-one variant or incomplete fix of CVE-2005-0312.
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Analysis
by VulDB Data Team • 04/26/2026
The War FTP Daemon version 1.82.00-RC11 contains a critical vulnerability that enables authenticated remote attackers to induce a denial of service condition through carefully crafted format string manipulation. This vulnerability specifically targets multiple file system commands including Change Working Directory CWD, Change to Parent Directory CDUP, Delete DELE, Name List NLST, List LIST, and Size SIZE commands. The flaw exploits improper input validation and format string handling mechanisms within the FTP daemon implementation, allowing malicious users to inject excessive "%s" format specifiers that can overwhelm the server's processing capabilities.
The technical implementation of this vulnerability stems from inadequate sanitization of user-supplied input parameters passed to format string functions within the daemon's command processing pipeline. When authenticated users submit commands containing a large number of format specifiers, the daemon's internal string handling routines become overwhelmed, leading to memory corruption or excessive CPU consumption that results in service unavailability. This represents a classic buffer overflow vulnerability variant that leverages format string manipulation rather than direct memory corruption techniques. The vulnerability aligns with CWE-134 which specifically addresses the use of format strings from untrusted sources, and the attack pattern corresponds to the ATT&CK technique T1499.004 for Network Denial of Service.
The operational impact of this vulnerability extends beyond simple service disruption as it affects the core functionality of the FTP daemon, potentially rendering the entire file transfer service unavailable to legitimate users. The attack requires only authenticated access, making it particularly dangerous as it can be exploited by authorized users with minimal privileges, potentially leading to privilege escalation scenarios or unauthorized data access. Organizations relying on WarFTPd for file transfer operations face significant risk of operational disruption, with potential business impact ranging from temporary service unavailability to complete system compromise. The vulnerability's potential relationship to CVE-2005-0312 suggests this may represent an incomplete fix or variant of a previously identified format string vulnerability, indicating poor code maintenance practices and insufficient security testing during the development lifecycle.
Mitigation strategies should focus on immediate patch deployment from the vendor, though given the age of this vulnerability and the specific version affected, organizations may need to consider migrating to more modern FTP implementations. Input validation controls should be implemented at the application level to sanitize command parameters and limit the number of format specifiers allowed in user input. Network segmentation and access controls can limit the attack surface by restricting which authenticated users can access the vulnerable commands. Additionally, monitoring systems should be configured to detect unusual command patterns that might indicate exploitation attempts, and regular security audits should verify proper input handling implementations across all FTP daemon components. The vulnerability demonstrates the critical importance of proper format string handling in network services and the necessity of comprehensive security testing throughout the software development lifecycle.