CVE-1999-1542 in Linux
Summary
by MITRE
RPMMail before 1.4 allows remote attackers to execute commands via an e-mail message with shell metacharacters in the "MAIL FROM" command.
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Analysis
by VulDB Data Team • 04/19/2026
The vulnerability identified as CVE-1999-1542 affects RPMMail versions prior to 1.4, representing a critical command injection flaw within email processing systems. This vulnerability exists in the handling of email messages where the MAIL FROM command contains shell metacharacters, creating a pathway for remote attackers to execute arbitrary commands on the affected system. The flaw stems from insufficient input validation and sanitization of email headers, particularly the MAIL FROM field which is commonly used in SMTP communication protocols. The vulnerability allows attackers to manipulate the email processing pipeline by injecting malicious shell commands through email headers, effectively bypassing normal email filtering mechanisms and gaining unauthorized access to the underlying system.
The technical implementation of this vulnerability involves the improper handling of user-supplied data within the email processing framework. When RPMMail receives an email message, it processes the MAIL FROM command without adequate sanitization of special shell characters such as semicolons, pipes, or backticks. This creates an environment where attackers can inject command sequences that get executed by the system's shell interpreter. The vulnerability is classified under CWE-78 as "Improper Neutralization of Special Elements used in an OS Command," which is a well-documented weakness in software systems that fail to properly escape or quote shell metacharacters. The attack vector operates through standard SMTP communication channels, making it particularly dangerous as it can be exploited through normal email traffic without requiring special privileges or authentication.
The operational impact of CVE-1999-1542 extends beyond simple command execution to encompass full system compromise capabilities. Attackers can leverage this vulnerability to gain unauthorized access to system resources, execute malicious code, modify system configurations, or even establish persistent backdoors within the affected environment. The vulnerability can be exploited through various attack techniques that align with the MITRE ATT&CK framework under the T1059.001 tactic of "Command and Scripting Interpreter: PowerShell" and T1078.004 tactic of "Valid Accounts: Cloud Accounts" when considering the broader attack surface. The vulnerability particularly affects systems that rely on RPMMail for email processing and may be exploited in conjunction with other vulnerabilities to escalate privileges or conduct more sophisticated attacks. Organizations using affected versions of RPMMail face significant risk of unauthorized system access and potential data breaches.
Mitigation strategies for CVE-1999-1542 primarily focus on immediate software updates and implementation of robust input validation measures. The most effective immediate solution involves upgrading to RPMMail version 1.4 or later, which includes proper sanitization of email headers and implementation of secure command execution practices. Organizations should also implement email filtering solutions that can detect and block suspicious email headers containing shell metacharacters. Network-level defenses such as firewalls and email security appliances can be configured to monitor for unusual email traffic patterns that may indicate exploitation attempts. Additional protective measures include implementing principle of least privilege for email processing accounts, regular security auditing of email systems, and deployment of intrusion detection systems to monitor for exploitation attempts. The vulnerability serves as a reminder of the critical importance of proper input validation and the potential consequences of inadequate sanitization of user-supplied data in system components that interact with operating system commands.