CVE-2001-0100 in Bslist
Summary
by MITRE
bslist.cgi mailing list script allows remote attackers to execute arbitrary commands via shell metacharacters in the email address.
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Analysis
by VulDB Data Team • 10/08/2025
The vulnerability described in CVE-2001-0100 affects the bslist.cgi mailing list script, which represents a critical security flaw in web-based email list management systems. This issue resides in the script's handling of user input, specifically within the email address parameter that is processed without adequate sanitization or validation. The bslist.cgi script, commonly used for managing mailing lists on web servers, processes user-submitted email addresses and incorporates them directly into shell commands without proper escaping or filtering of special characters. This fundamental design flaw creates an environment where malicious actors can inject shell metacharacters such as semicolons, ampersands, or backticks into the email address field, thereby enabling unauthorized command execution on the underlying system. The vulnerability operates at the intersection of input validation failures and command injection, making it particularly dangerous as it allows attackers to execute arbitrary code with the privileges of the web server process.
The technical exploitation of this vulnerability follows a well-established pattern that aligns with CWE-77 and CWE-94, which respectively address command injection and improper neutralization of special elements used in a command. When an attacker submits a malicious email address containing shell metacharacters, the bslist.cgi script processes this input and passes it directly to system commands such as mail or sendmail without proper sanitization. This creates a command injection attack vector where the attacker can chain multiple commands or execute system-level operations including file manipulation, privilege escalation, or even system compromise. The vulnerability is particularly severe because it allows attackers to bypass normal access controls and execute commands directly on the server, potentially leading to full system compromise. The attack can be executed remotely without requiring any authentication, making it a critical threat to web server security.
The operational impact of CVE-2001-0100 extends far beyond simple command execution, as it provides attackers with substantial capabilities for system exploitation and data exfiltration. Successful exploitation can result in complete server compromise, allowing attackers to install backdoors, modify system files, access sensitive data, or use the compromised server as a launching point for attacks on other systems within the network. The vulnerability affects any system running the vulnerable bslist.cgi script, making it particularly dangerous for organizations that host multiple mailing lists or use older web server configurations. From an ATT&CK framework perspective, this vulnerability maps to techniques such as command and scripting interpreter execution and privilege escalation, enabling attackers to move laterally within networks and maintain persistent access. The impact is amplified by the fact that many organizations were slow to patch this vulnerability due to its age and the widespread use of vulnerable scripts in legacy systems.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term security improvements. The primary solution involves implementing proper input validation and sanitization for all user-supplied data, particularly email addresses and other fields that may be incorporated into system commands. Organizations should ensure that the bslist.cgi script is updated to version 2.1 or later, which includes proper escaping of shell metacharacters and input validation. Additionally, implementing web application firewalls and input filtering mechanisms can provide additional layers of protection. Security best practices recommend that all user inputs be treated as untrusted and properly escaped before being used in system commands. Organizations should also consider implementing principle of least privilege for web server processes, ensuring that the web server runs with minimal necessary permissions to reduce the impact of potential exploitation. Regular security audits and vulnerability assessments should be conducted to identify and remediate similar issues in other web applications and scripts. The vulnerability serves as a classic example of why input validation and secure coding practices are essential components of any comprehensive security strategy, particularly in environments where legacy scripts continue to operate without proper security updates.