CVE-2000-0416 in NTMail
Summary
by MITRE
NTMail 5.x allows network users to bypass the NTMail proxy restrictions by redirecting their requests to NTMail's web configuration server.
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Analysis
by VulDB Data Team • 04/21/2026
The vulnerability described in CVE-2000-0416 represents a critical security flaw in NTMail 5.x software that undermines the intended proxy restrictions designed to control network access. This issue affects Microsoft NTMail versions 5.x and demonstrates how web-based configuration services can be exploited to circumvent security controls. The vulnerability specifically targets the proxy enforcement mechanisms that are typically implemented to restrict unauthorized access to network resources and control the flow of requests between internal and external networks.
The technical flaw exploits the architecture of NTMail's web configuration server by allowing network users to redirect their requests directly to this component instead of routing through the properly configured proxy mechanisms. This redirection bypasses the security checks that would normally validate requests and enforce access controls. The vulnerability stems from insufficient input validation and improper access control implementation within the web configuration server, which fails to properly authenticate or authorize requests that are attempting to access restricted resources through alternative pathways.
From an operational impact perspective, this vulnerability creates a significant security risk for organizations relying on NTMail 5.x for email services and network access control. Attackers can leverage this flaw to gain unauthorized access to network resources that should be restricted through proxy controls, potentially leading to data breaches, unauthorized network access, and escalation of privileges. The vulnerability is particularly dangerous because it allows attackers to bypass security measures that are fundamental to network protection strategies. Organizations may experience unauthorized access to sensitive information, disruption of services, and potential compromise of their entire network infrastructure.
The security implications of this vulnerability align with CWE-284, which addresses improper access control, and can be mapped to ATT&CK technique T1071.004 for application layer protocol: web protocols. Organizations should implement immediate mitigations including disabling unnecessary web configuration services, implementing proper access controls and authentication mechanisms, and ensuring that network traffic is properly filtered through designated proxy servers. Additionally, network segmentation and monitoring of unusual traffic patterns can help detect exploitation attempts. Regular security updates and patches should be applied to address the underlying flaws in the NTMail implementation, while network administrators should review and strengthen proxy configurations to prevent similar redirection attacks. The vulnerability highlights the importance of proper input validation and access control implementation in web-based services, emphasizing that security controls must be robust against various attack vectors including redirection and bypass techniques.