CVE-2002-0799 in CMailServer
Summary
by MITRE
Buffer overflow in YoungZSoft CMailServer 3.30 allows remote attackers to execute arbitrary code via a long USER argument.
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Analysis
by VulDB Data Team • 09/13/2025
The vulnerability identified as CVE-2002-0799 represents a critical buffer overflow flaw within YoungZSoft CMailServer version 3.30 that exposes remote attackers to potential code execution capabilities. This issue specifically manifests when the server processes an overly long USER argument during authentication or communication protocols, creating a condition where memory boundaries are exceeded and potentially allowing malicious actors to overwrite adjacent memory locations with crafted payload data.
The technical implementation of this buffer overflow occurs at the protocol handling layer where the CMailServer application fails to properly validate the length of user input parameters. When a remote attacker submits a USER argument that exceeds the allocated buffer size, the application's memory management mechanisms become compromised, leading to potential memory corruption that can be exploited to redirect program execution flow. This type of vulnerability falls under the common weakness enumeration CWE-121, which specifically addresses stack-based buffer overflow conditions where insufficient bounds checking allows for memory overwrite scenarios.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as it provides attackers with the capability to execute arbitrary code on the affected system with the privileges of the mail server process. This remote code execution vulnerability enables attackers to gain unauthorized access to the server environment, potentially leading to complete system compromise, data exfiltration, or use as a pivot point for further network infiltration activities. The attack vector requires only a remote connection to the mail server and does not necessitate prior authentication, making it particularly dangerous in environments where mail servers are exposed to untrusted networks.
Security practitioners should recognize this vulnerability as a classic example of insufficient input validation that violates fundamental secure coding practices and aligns with ATT&CK technique T1059.007 for command and scripting interpreter. The vulnerability demonstrates how legacy mail server implementations often lack modern security protections such as stack canaries, address space layout randomization, or input length restrictions that would prevent such exploitation scenarios. Organizations should implement immediate mitigations including patching to newer versions of CMailServer, network segmentation to limit exposure, and deployment of intrusion detection systems to monitor for suspicious USER argument patterns that could indicate exploitation attempts. Additionally, firewall rules should restrict access to mail server ports from trusted networks only, while regular security audits should verify that all mail server components are running patched versions that address known buffer overflow vulnerabilities.