CVE-2009-5011: Race condition in the FTPHandler class in ftpserver.py in pyftpdlib before 0.5.2 allows remote attackers to...

Security readout for executives and security teams

CVE-2009-5011 is a remote denial-of-service issue in pyftpdlib before 0.5.2. A client that connects and disconnects very quickly can trigger a race condition that may take the FTP daemon offline. The available record does not show data theft, code execution, or confirmed active exploitation. Exposure is most likely where pyftpdlib versions before 0.5.2 are used to provide FTP services reachable by untrusted networks. The source bundle does not identify specific downstream products, packages, or appliances. Treat this as an availability risk for legacy FTP services. Prioritize internet-facing or business-critical FTP endpoints first. It is not currently evidenced as exploited in the wild, but an unauthenticated remote outage can still disrupt operations. Mitigation focus: Identify systems running pyftpdlib-based FTP services.; Upgrade pyftpdlib to 0.5.2 or later where applicable.; Restrict FTP access to trusted networks when possible..

Prepared

Jun 28, 2026, 01:40 UTC (UTC+00:00)

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.