CVE-2003-0391 in Magic Winmail Server
Summary
by MITRE
Format string vulnerability in Magic WinMail Server 2.3, and possibly other 2.x versions, allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via format string specifiers in the PASS command.
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Analysis
by VulDB Data Team • 08/17/2025
The vulnerability identified as CVE-2003-0391 represents a critical format string vulnerability affecting Magic WinMail Server version 2.3 and potentially other versions within the 2.x series. This flaw exists within the server's handling of authentication commands, specifically the PASS command used during user authentication processes. The vulnerability stems from improper input validation and sanitization of user-supplied data that is subsequently processed through format string functions without adequate protection against malicious formatting sequences.
The technical implementation of this vulnerability occurs when the server receives a specially crafted PASS command containing format string specifiers such as %s, %d, or other format directives. These specifiers are typically used in programming languages like C to control output formatting, but when processed with untrusted input, they can cause the application to read from arbitrary memory locations or execute unintended operations. The flaw allows attackers to manipulate the program's execution flow by injecting these format specifiers, potentially leading to stack corruption, memory access violations, or even arbitrary code execution depending on the specific implementation and memory layout.
From an operational impact perspective, this vulnerability presents a significant risk to email server infrastructure as it enables remote attackers to cause system crashes and potentially gain unauthorized code execution capabilities. The denial of service aspect means that legitimate users could be denied access to email services, while the arbitrary code execution potential allows for complete system compromise. This vulnerability directly impacts the availability, integrity, and confidentiality of email services, making it a critical concern for organizations relying on Magic WinMail Server for their email infrastructure. The attack surface is particularly concerning as it requires no authentication to exploit, making it accessible to any remote attacker with network access to the server.
Mitigation strategies for this vulnerability should include immediate patching of affected systems to the latest available versions of Magic WinMail Server that address the format string handling issues. Organizations should also implement network segmentation to limit access to email servers, deploy intrusion detection systems to monitor for suspicious authentication patterns, and consider implementing additional access controls such as IP whitelisting for authentication endpoints. The vulnerability aligns with CWE-134 which specifically addresses the use of format strings in security-sensitive contexts, and it maps to ATT&CK technique T1210 for exploitation of vulnerabilities in remote services. Regular security assessments and vulnerability scanning should be conducted to identify similar issues in other email server implementations and ensure comprehensive protection against format string vulnerabilities across the organization's infrastructure.