CVE-2007-4565: sink.c in fetchmail before 6.3.9 allows context-dependent attackers to cause a denial of service (NULL dere...

Security readout for executives and security teams

CVE-2007-4565 is a denial-of-service flaw in fetchmail before 6.3.9. Under specific SMTP warning-message handling conditions, an attacker can trigger a NULL dereference that crashes the application. The business risk is mail retrieval disruption, not data theft or system takeover based on the supplied sources. Exposure is most likely on legacy Unix, Linux, or macOS systems still running fetchmail versions older than 6.3.9. Modern systems are likely patched, but embedded, unattended, or rarely updated mail retrieval hosts may retain exposure. Treat as a hygiene and continuity issue. It is old and not KEV-listed, but unpatched fetchmail can interrupt mail retrieval. Address during legacy-system patching unless the service supports business-critical mail flows. Mitigation focus: Upgrade fetchmail to 6.3.9 or a vendor-supported fixed package.; Check operating system vendor advisories for backported fetchmail fixes.; Prioritize legacy mail retrieval hosts and unattended automation systems..

Prepared

Jun 29, 2026, 03:52 UTC (UTC+00:00)

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