CVE-2000-0557 in CMail
Summary
by MITRE
Buffer overflow in the web interface for Cmail 2.4.7 allows remote attackers to execute arbitrary commands via a long GET request.
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Analysis
by VulDB Data Team • 04/21/2026
The vulnerability identified as CVE-2000-0557 represents a critical buffer overflow flaw within the web interface of Cmail version 2.4.7, a mail server software widely used in enterprise environments during the late 1990s and early 2000s. This security weakness resides in the application's handling of HTTP GET requests, specifically when processing user-supplied input through the web-based administrative interface. The buffer overflow occurs when the application fails to properly validate or limit the length of input parameters received via HTTP GET requests, creating an exploitable condition that can be leveraged by remote attackers to gain unauthorized system access.
The technical implementation of this vulnerability stems from inadequate input validation mechanisms within the Cmail web interface codebase. When a remote attacker crafts a specially formatted GET request containing an excessively long parameter value, the application's buffer management routines fail to handle the overflow gracefully. This condition typically manifests in the application's string handling functions where fixed-size buffers are used to store user input without proper bounds checking. The flaw aligns with CWE-121, which categorizes buffer overflow conditions occurring in stack-based buffers, and represents a classic example of unsafe string manipulation practices that were prevalent in legacy software implementations of that era. The vulnerability essentially allows an attacker to overwrite adjacent memory locations, potentially corrupting program execution flow and enabling arbitrary code execution.
The operational impact of CVE-2000-0557 extends beyond simple unauthorized access, as successful exploitation can lead to complete system compromise and persistent backdoor access. Attackers can leverage this vulnerability to execute arbitrary commands with the privileges of the web server process, which typically runs with elevated permissions to manage email services. The attack vector requires only a web browser or HTTP client capable of sending GET requests, making it particularly dangerous as it can be exploited through automated scanning tools or web-based attack frameworks. This vulnerability directly maps to ATT&CK technique T1059.007, which describes the execution of commands through web shells or similar interfaces, and T1203, which covers the exploitation of vulnerabilities in web applications to gain unauthorized access. Organizations using Cmail 2.4.7 were particularly vulnerable as the software was commonly deployed in corporate environments where email systems served as critical infrastructure components.
Mitigation strategies for CVE-2000-0557 require immediate action including patching or upgrading to a newer version of Cmail that addresses the buffer overflow vulnerability, as the original vendor likely released a security update to resolve this issue. Organizations should implement network-based firewalls and intrusion detection systems to monitor for suspicious GET request patterns that may indicate exploitation attempts, particularly those with unusually long parameter values. Additionally, input validation measures should be implemented at the application level to enforce strict length limitations on all user-supplied parameters, and web application firewalls can provide an additional layer of protection by filtering malformed HTTP requests. The vulnerability demonstrates the importance of proper software security practices including bounds checking, input validation, and regular security updates, aligning with security frameworks such as OWASP Top Ten and NIST cybersecurity guidelines that emphasize the prevention of buffer overflow conditions through secure coding practices.