CVE-1999-1012 in Domino
Summary
by MITRE
SMTP component of Lotus Domino 4.6.1 on AS/400, and possibly other operating systems, allows a remote attacker to crash the mail server via a long string.
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Analysis
by VulDB Data Team • 04/19/2026
The vulnerability identified as CVE-1999-1012 represents a classic buffer overflow condition affecting the Simple Mail Transfer Protocol implementation within IBM Lotus Domino 4.6.1 running on AS/400 systems and potentially other platforms. This flaw resides in the SMTP component's handling of incoming mail data, specifically when processing malformed or excessively long string inputs. The vulnerability operates at the application layer and demonstrates how insufficient input validation can lead to system instability and denial of service conditions. The issue stems from the lack of proper bounds checking in the mail server's string processing functions, creating an exploitable condition where an attacker can send specially crafted email messages containing excessive data lengths.
The technical implementation of this vulnerability involves the SMTP service's inability to properly manage memory allocation when processing incoming email headers or body content. When a remote attacker sends an email message containing a string that exceeds the allocated buffer space, the application experiences memory corruption that results in an immediate crash of the mail server process. This behavior aligns with CWE-121, which describes heap-based buffer overflow conditions, and CWE-122, which covers stack-based buffer overflow scenarios. The vulnerability affects the core mail processing functionality and can be exploited through standard network-based attacks without requiring authentication or privileged access. The attack vector operates over TCP port 25, which is the standard SMTP port, making it accessible to any remote attacker with network connectivity to the target system.
The operational impact of CVE-1999-1012 extends beyond simple service disruption to potentially compromise the availability of email services for an entire organization. When exploited successfully, the vulnerability causes the Domino mail server to crash and restart, resulting in temporary loss of email functionality for users within the affected domain. This type of denial of service attack can be particularly damaging in enterprise environments where email communications are critical for business operations. The vulnerability also demonstrates how legacy systems can contain fundamental security flaws that persist across multiple versions and platforms, highlighting the importance of proper input validation and memory management in server applications. Organizations using Lotus Domino 4.6.1 may experience cascading effects from this vulnerability as email services become unavailable, potentially disrupting business processes that depend on email communication.
Mitigation strategies for CVE-1999-1012 should focus on both immediate protective measures and long-term architectural improvements. The most effective immediate solution involves applying the vendor-provided security patches and updates that address the buffer overflow condition in the SMTP component. Organizations should also implement network-level protections such as email filtering systems that can detect and block malformed email traffic before it reaches the mail server. Network segmentation and firewall rules can be configured to limit access to port 25 from trusted sources only, reducing the attack surface. Additionally, implementing intrusion detection systems that monitor for unusual email traffic patterns can help identify potential exploitation attempts. From a defensive standpoint, this vulnerability highlights the importance of following secure coding practices including input validation, proper memory management, and regular security assessments. The ATT&CK framework categorizes this type of vulnerability under the 'Exploitation for Privilege Escalation' and 'Denial of Service' tactics, emphasizing the need for layered security approaches that protect against both unauthorized access and service disruption attacks.