CVE-2009-0884 in FileZilla Server
Summary
by MITRE
Buffer overflow in FileZilla Server before 0.9.31 allows remote attackers to cause a denial of service via unspecified vectors related to SSL/TLS packets.
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Analysis
by VulDB Data Team • 04/20/2025
The vulnerability identified as CVE-2009-0884 represents a critical buffer overflow flaw within FileZilla Server versions prior to 0.9.31. This issue specifically affects the server's handling of SSL/TLS packets, creating a potential avenue for remote attackers to execute denial of service attacks. The vulnerability stems from inadequate input validation and memory management practices within the server's secure communication protocols implementation.
The technical flaw manifests when the FileZilla Server processes incoming SSL/TLS packets that contain malformed or excessively large data structures. This buffer overflow condition occurs during the SSL/TLS handshake process or while processing encrypted data streams, where the server fails to properly validate the size and content of incoming packets before attempting to store them in fixed-size memory buffers. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, where insufficient bounds checking allows attackers to overwrite adjacent memory locations and potentially corrupt program execution flow.
Operationally, this vulnerability presents significant risks to organizations relying on FileZilla Server for file transfer operations. Remote attackers can exploit this flaw to crash the server process, resulting in complete denial of service for legitimate users attempting to access file transfer services. The attack vector requires no authentication and can be executed from any network location, making it particularly dangerous in production environments. The impact extends beyond simple service disruption as the vulnerability could potentially be leveraged for more sophisticated attacks if combined with other exploitation techniques, though the primary threat remains denial of service.
The security implications of this vulnerability align with ATT&CK technique T1499.004 which covers network denial of service attacks. Organizations using FileZilla Server versions before 0.9.31 face increased risk of service interruptions that can impact business operations and user productivity. The vulnerability demonstrates poor software security practices in handling network protocols and highlights the importance of proper input validation in cryptographic implementations. Mitigation strategies should include immediate patching to version 0.9.31 or later, implementing network segmentation to limit exposure, and monitoring for unusual connection patterns or service disruptions that may indicate exploitation attempts. Additionally, organizations should consider implementing intrusion detection systems to monitor for potential exploitation attempts targeting this specific vulnerability.