CVE-1999-0047 in Sendmail
Summary
by MITRE
mime conversion buffer overflow in sendmail versions 8.8.3 and 8.8.4.
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Analysis
by VulDB Data Team • 10/28/2025
The vulnerability described in CVE-1999-0047 represents a critical buffer overflow condition within the sendmail mail transfer agent version 8.8.3 and 8.8.4. This flaw specifically manifests during the processing of mime conversion operations, where the software fails to properly validate input lengths before copying data into fixed-size buffers. The vulnerability arises from inadequate bounds checking mechanisms that allow maliciously crafted email messages to trigger memory corruption when the system attempts to process mime encoded content.
This buffer overflow vulnerability falls under the CWE-121 category of stack-based buffer overflow, which occurs when data is copied into a buffer located on the stack without proper size validation. The technical implementation flaw exists in the mime conversion handling code path where sendmail processes multipart email messages containing encoded content. When an attacker crafts a specially formatted email with excessive data in mime headers or encoded content sections, the system's internal buffers overflow, potentially allowing arbitrary code execution.
The operational impact of this vulnerability is severe as it enables remote code execution on systems running vulnerable sendmail versions. Attackers can exploit this weakness by sending malicious email messages that contain oversized mime encoded data, causing the sendmail process to crash or potentially execute arbitrary commands with the privileges of the mail daemon. This represents a significant threat to email server security as it allows unauthorized individuals to gain control of mail servers without requiring authentication. The vulnerability affects systems where sendmail processes incoming email messages, making it particularly dangerous for internet-facing mail servers.
Mitigation strategies for CVE-1999-0047 include immediate patching of sendmail installations to versions 8.8.5 or later, which contain fixes for the mime conversion buffer overflow. System administrators should also implement email filtering mechanisms that validate and sanitize incoming mime content before it reaches the sendmail processing engine. Network-level defenses such as firewalls and intrusion detection systems can help monitor for suspicious email traffic patterns that may indicate exploitation attempts. Additionally, implementing proper input validation and bounds checking in all email processing components aligns with the principles outlined in the software security guidance referenced in the ATT&CK framework's technique T1190 for exploitation through email. Organizations should also consider implementing email security solutions that can detect and block malicious mime content before it reaches the mail server, reducing the attack surface and providing defense-in-depth measures against similar buffer overflow vulnerabilities.