CVE-2004-1533 in Pop3 Server
Summary
by MITRE
Buffer overflow in pop3svr.exe for DMS POP3 1.5.3.27 and earlier allows remote attackers to cause a denial of service (service crash) via a long (1) username or (2) password.
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Analysis
by VulDB Data Team • 07/06/2025
The vulnerability identified as CVE-2004-1533 represents a critical buffer overflow flaw within the pop3svr.exe component of DMS POP3 server version 1.5.3.27 and earlier implementations. This security weakness manifests when the server processes authentication requests containing excessively long username or password parameters, creating a condition where memory boundaries are exceeded during data handling operations. The flaw specifically targets the POP3 service implementation, which forms a fundamental component of email communication infrastructure and serves as an entry point for numerous email client applications.
The technical nature of this vulnerability aligns with CWE-121, which categorizes buffer overflow conditions where insufficient bounds checking occurs during data processing. The flaw operates by accepting user input without proper validation of length constraints, allowing attackers to supply maliciously crafted strings that exceed the allocated buffer space. When the pop3svr.exe process attempts to store these oversized credentials, it overwrites adjacent memory locations, potentially causing unpredictable behavior including application crashes, stack corruption, or in more severe cases, arbitrary code execution. The vulnerability's impact is particularly concerning as it affects the core authentication mechanism of the POP3 server, making it a prime target for denial of service attacks that can effectively disrupt email services for legitimate users.
Operationally, this vulnerability creates significant risks for organizations relying on DMS POP3 server implementations, as remote attackers can easily exploit the flaw to cause service disruption without requiring authentication or specialized tools. The attack vector is straightforward, requiring only the ability to connect to the POP3 service and submit malformed credentials, making it accessible to attackers with minimal technical expertise. The resulting denial of service condition can lead to complete email service unavailability, affecting business operations and potentially causing data communication failures. From an attack framework perspective, this vulnerability maps to the ATT&CK technique T1499.004 which covers network denial of service attacks, and represents a classic example of how insufficient input validation can lead to service disruption.
Organizations should implement immediate mitigations including upgrading to patched versions of DMS POP3 server software, applying the vendor-supplied security patches, and implementing network-level controls such as rate limiting and connection filtering to prevent exploitation attempts. System administrators should also consider implementing intrusion detection systems that can identify unusual authentication patterns and monitor for potential exploitation attempts. Additionally, network segmentation strategies can limit the impact of successful exploitation by isolating the vulnerable POP3 service from critical infrastructure components. The vulnerability serves as a reminder of the critical importance of input validation and proper memory management in server applications, particularly those handling authentication credentials where the consequences of exploitation can extend far beyond simple service disruption to impact business continuity and data availability.