CVE-1999-0206 in Sendmail
Summary
by MITRE
mime buffer overflow in sendmail 8.8.0 and 8.8.1 gives root access.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 10/26/2025
The vulnerability described in CVE-1999-0206 represents a critical buffer overflow flaw within the sendmail email transfer agent version 8.8.0 and 8.8.1. This issue specifically affects the mime processing functionality where the software fails to properly validate input length when handling mime-encoded messages. The flaw exists in the way sendmail processes multipart mime messages, particularly when dealing with overly long header fields or body content that exceeds predetermined buffer boundaries. The vulnerability stems from inadequate bounds checking mechanisms that allow maliciously crafted email messages to overwrite adjacent memory locations in the sendmail process.
The technical exploitation of this vulnerability occurs when an attacker sends a specially crafted email message containing malformed mime content that triggers the buffer overflow condition. When the sendmail daemon processes this malformed message, the overflow corrupts the stack memory, potentially allowing an attacker to overwrite return addresses and execute arbitrary code with the privileges of the sendmail process. Since sendmail typically runs with root privileges due to its role in system email handling, successful exploitation directly results in complete system compromise. The vulnerability is classified as a classic stack-based buffer overflow with a severity rating that reflects its potential for privilege escalation and system takeover.
The operational impact of this vulnerability extends beyond simple exploitation as it affects thousands of systems running vulnerable versions of sendmail. Organizations relying on sendmail for email services face significant risk of unauthorized access, data breaches, and complete system control. The vulnerability is particularly dangerous in multi-user environments where sendmail serves as the primary email gateway, as it provides a direct path for attackers to gain elevated system privileges. Network administrators must consider that this vulnerability could be exploited remotely without authentication, making it a prime target for automated attack tools. The widespread deployment of sendmail across unix and linux systems during this period amplifies the potential scope of impact, as many systems would have been vulnerable to this specific memory corruption issue.
Mitigation strategies for CVE-1999-0206 require immediate action to upgrade sendmail to versions that address the buffer overflow conditions. The most effective approach involves patching to sendmail version 8.8.2 or later, which includes proper bounds checking for mime processing routines. System administrators should also implement additional protective measures such as restricting sendmail's network access, implementing email filtering rules to block suspicious mime content, and monitoring for unusual email processing patterns. From a compliance perspective, this vulnerability aligns with CWE-121 which describes stack-based buffer overflow conditions, and could be categorized under ATT&CK technique T1059 for command and scripting interpreter usage. Organizations should also consider implementing network segmentation to limit exposure, disable unnecessary sendmail features, and establish robust email security policies that include regular vulnerability scanning and patch management procedures. The vulnerability demonstrates the critical importance of input validation in system security and highlights why buffer overflow protections are essential for critical system services.