CVE-1999-0846 in MDaemon
Summary
by MITRE
Denial of service in MDaemon 2.7 via a large number of connection attempts.
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Analysis
by VulDB Data Team • 04/19/2026
The vulnerability described in CVE-1999-0846 represents a classic denial of service attack vector targeting the MDaemon email server software version 2.7. This issue manifests when an attacker floods the system with an excessive number of connection attempts, ultimately leading to service disruption and unavailability for legitimate users. The MDaemon email server, widely deployed in enterprise environments for email management, becomes vulnerable to this attack due to insufficient connection handling mechanisms and lack of rate limiting capabilities. The vulnerability specifically affects the server's ability to manage concurrent connections properly, creating a scenario where legitimate connection requests cannot be processed due to resource exhaustion.
The technical flaw underlying this vulnerability stems from inadequate input validation and connection management within the MDaemon server implementation. When multiple connection attempts are received simultaneously, the server fails to properly queue or throttle these requests, resulting in a resource exhaustion condition that prevents normal operation. This weakness aligns with CWE-400, which categorizes unchecked resource consumption as a significant security concern. The server's architecture does not implement proper connection rate limiting or connection pooling mechanisms that would normally protect against such attacks. Attackers can exploit this by establishing numerous concurrent connections without proper authentication or legitimate purpose, overwhelming the system's ability to maintain service availability. The vulnerability operates at the network layer and application layer, making it particularly effective against email servers that must maintain open ports for client connections.
The operational impact of this vulnerability extends beyond simple service disruption, potentially affecting business continuity and email communication workflows within organizations. When an MDaemon server becomes unavailable due to this denial of service attack, email services across the affected organization cease to function properly, impacting productivity and customer communications. The attack requires minimal resources from the attacker's perspective, making it particularly dangerous as it can be executed by anyone with network access to the target system. Organizations relying on MDaemon for email services face significant risk, as the attack can be executed without requiring special privileges or advanced technical knowledge. The vulnerability affects the availability aspect of the CIA triad, specifically targeting the system's ability to provide uninterrupted service to authorized users.
Mitigation strategies for this vulnerability should focus on implementing proper network-level protections and server configuration hardening measures. Organizations should deploy firewall rules that limit the number of connections from individual IP addresses and implement connection rate limiting at the network perimeter. The recommended approach includes configuring the MDaemon server to enforce connection limits and implementing proper logging mechanisms to detect unusual connection patterns. Network administrators should also consider implementing intrusion detection systems that can identify and block excessive connection attempts. According to ATT&CK framework, this vulnerability maps to technique T1499 which covers network denial of service attacks. The most effective long-term solution involves upgrading to a patched version of MDaemon that includes proper connection handling and rate limiting features. Additionally, implementing proper monitoring and alerting systems can help detect and respond to such attacks before they cause significant disruption to email services.