CVE-1999-1224 in Imapd
Summary
by MITRE
IMAP 4.1 BETA, and possibly other versions, does not properly handle the SIGABRT (abort) signal, which allows local users to crash the server (imapd) via certain sequences of commands, which causes a core dump that may contain sensitive password information.
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Analysis
by VulDB Data Team • 04/17/2026
The vulnerability described in CVE-1999-1224 affects IMAP 4.1 BETA and potentially other versions of the IMAP server implementation. This represents a critical security flaw in the mail server's signal handling mechanism that can be exploited by local attackers to cause system instability and potential information disclosure. The issue stems from improper handling of the SIGABRT signal, which is a standard Unix signal used to request program termination. When this signal is received by the imapd server process, the application fails to manage it correctly, leading to an uncontrolled crash that generates a core dump file.
The technical exploitation of this vulnerability involves sending specific sequences of IMAP commands that trigger the SIGABRT signal handling error. When the imapd process receives this signal, it terminates abnormally without proper cleanup procedures, resulting in a core dump file being generated on the system. These core dump files contain the complete memory state of the process at the time of termination, including sensitive information such as user passwords and other authentication credentials. This memory dump mechanism creates a significant information disclosure risk that can be leveraged by attackers to obtain authentication tokens and other confidential data.
The operational impact of this vulnerability extends beyond simple service disruption to encompass serious data security concerns. Local users who can access the system can exploit this flaw to crash the IMAP server repeatedly, potentially causing denial of service conditions that affect legitimate users. More critically, the core dump files generated during these crashes may contain plaintext passwords and other sensitive authentication information, creating a gold mine for attackers who can access these memory dumps. The vulnerability is particularly dangerous in multi-user environments where local access might be obtained through various means such as compromised accounts or privilege escalation attacks.
This vulnerability aligns with CWE-174, which addresses the weakness of insufficient signal handling in applications, and represents a classic example of improper error handling that can lead to both availability and confidentiality breaches. From an attack perspective, this flaw maps to techniques described in the MITRE ATT&CK framework under the T1499 category for endpoint disruption and potentially T1566 for credential access through information discovery. The vulnerability demonstrates poor defensive programming practices where signal handlers are not properly implemented to handle abnormal termination conditions, creating a security boundary failure that allows attackers to bypass normal authentication and authorization mechanisms.
Organizations should implement immediate mitigations including updating to patched versions of the IMAP server software, implementing proper signal handling mechanisms that prevent core dumps from containing sensitive information, and configuring the system to disable core dump generation for privileged processes. Additionally, monitoring for unusual process termination patterns and implementing proper access controls to limit local user privileges can significantly reduce the risk exposure. Security administrators should also consider implementing network segmentation to limit local access to mail server processes and ensure that core dump files are properly secured and rotated to prevent unauthorized access to sensitive information.