CVE-2000-0158 in OpenServer
Summary
by MITRE
Buffer overflow in MMDF server allows remote attackers to gain privileges via a long MAIL FROM command to the SMTP daemon.
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Analysis
by VulDB Data Team • 04/20/2026
The vulnerability identified as CVE-2000-0158 represents a critical buffer overflow flaw within the MMDF (Mail Message Distribution Facility) server implementation that affects the SMTP daemon component. This vulnerability stems from inadequate input validation mechanisms within the mail server's command processing logic, specifically when handling the MAIL FROM command which is fundamental to smtp protocol operations. The flaw occurs when the server receives a malformed MAIL FROM command containing excessive data that exceeds the allocated buffer space, creating conditions where adjacent memory regions become overwritten with attacker-controlled data.
The technical implementation of this vulnerability resides in the server's handling of user input without proper bounds checking or length validation. When the SMTP daemon processes the MAIL FROM command, it fails to enforce strict limits on the length of the sender address specification, allowing remote attackers to craft malicious input sequences that exceed the predetermined buffer boundaries. This buffer overflow condition creates opportunities for arbitrary code execution within the context of the running SMTP daemon process, potentially elevating privileges from standard user level to system level access depending on how the service is configured and running.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass complete system compromise and potential data exfiltration capabilities. An attacker exploiting this flaw could gain unauthorized access to the mail server system, potentially leading to unauthorized email relay, message interception, or even complete system takeover. The vulnerability affects systems running MMDF implementations that utilize the affected SMTP daemon, making it particularly concerning for organizations relying on legacy mail infrastructure. The remote nature of the attack vector means that exploitation can occur from any network location without requiring physical access to the target system.
Mitigation strategies for CVE-2000-0158 should prioritize immediate patch application from the vendor or implementation of network-based protections such as intrusion detection systems that can identify and block malformed MAIL FROM commands. Organizations should implement strict input validation at network boundaries and consider deploying SMTP filtering solutions that can detect and prevent oversized command sequences. The vulnerability aligns with CWE-121 which describes heap-based buffer overflow conditions, and maps to ATT&CK technique T1059.007 for command and scripting interpreter execution. System administrators should also consider implementing least privilege principles for mail server processes and regularly audit mail server configurations to ensure that unnecessary services are disabled. Network segmentation and firewall rules can provide additional protection layers by limiting access to mail server ports and monitoring traffic patterns for anomalous command sequences.