CVE-2000-0859 in NTMail
Summary
by MITRE
The web configuration server for NTMail V5 and V6 allows remote attackers to cause a denial of service via a series of partial HTTP requests.
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Analysis
by VulDB Data Team • 10/12/2025
The vulnerability described in CVE-2000-0859 represents a significant denial of service weakness in the NTMail web configuration server software versions 5 and 6. This flaw exists within the HTTP request processing mechanism of the mail server's web interface, creating a pathway for remote attackers to disrupt service availability. The vulnerability specifically targets the server's handling of partial HTTP requests, which are incomplete HTTP transactions that may be sent as part of a larger communication sequence. This type of attack demonstrates a fundamental weakness in the server's request parsing and resource management capabilities, as it fails to properly handle malformed or incomplete HTTP communications.
The technical implementation of this vulnerability stems from inadequate input validation and resource handling within the NTMail web configuration server. When the server receives a series of partial HTTP requests, it fails to properly terminate or handle these incomplete transactions, leading to resource exhaustion or system instability. This behavior aligns with CWE-400, which categorizes "Uncontrolled Resource Consumption" as a common weakness in software systems. The server's inability to gracefully handle malformed HTTP requests results in a cascading failure that can consume system resources such as memory, CPU cycles, or connection handles, ultimately rendering the service unavailable to legitimate users. The vulnerability operates at the application layer of the network stack, making it particularly dangerous as it can be exploited without requiring authentication or privileged access.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the overall reliability and availability of email services. Organizations relying on NTMail V5 and V6 for their email infrastructure face significant risk of unauthorized denial of service attacks that can last for extended periods. The attack vector allows remote exploitation, meaning that adversaries can initiate these attacks from anywhere on the internet without requiring physical access to the network or system. This vulnerability directly impacts the availability component of the CIA triad, as it compromises the ability of authorized users to access email services. The consequences can include business disruption, loss of productivity, and potential financial impact due to extended service outages.
Mitigation strategies for this vulnerability must address both immediate protection and long-term system hardening. The most effective immediate solution involves applying vendor patches or updates that specifically address the HTTP request handling flaw in the affected NTMail versions. Organizations should also implement network-level protections such as rate limiting and connection throttling to prevent exploitation through partial HTTP request sequences. Security monitoring should be enhanced to detect unusual patterns of partial HTTP requests that may indicate attempted exploitation. Additionally, system administrators should consider implementing intrusion detection systems that can identify and alert on suspicious HTTP traffic patterns. The remediation process should include comprehensive testing to ensure that the applied fixes do not introduce compatibility issues with existing email services or configurations. Organizations should also review their broader security posture and consider implementing defense-in-depth strategies that include network segmentation and access controls to limit the potential impact of similar vulnerabilities in other system components. This vulnerability serves as a reminder of the critical importance of proper input validation and resource management in web server implementations, aligning with ATT&CK technique T1499 for network denial of service attacks and emphasizing the need for robust application security practices.