CVE-2002-1827 in Sendmail
Summary
by MITRE
Sendmail 8.9.0 through 8.12.3 allows local users to cause a denial of service by obtaining an exclusive lock on the (1) alias, (2) map, (3) statistics, and (4) pid files.
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Analysis
by VulDB Data Team • 09/01/2025
The vulnerability described in CVE-2002-1827 represents a significant denial of service weakness within the Sendmail mail transfer agent versions 8.9.0 through 8.12.3. This issue stems from the software's handling of file locking mechanisms during critical operational processes. The vulnerability specifically affects four key file types: alias files, map files, statistics files, and pid files, all of which are essential components for proper mail server functionality. When local users exploit this weakness, they can obtain exclusive locks on these files, effectively preventing the Sendmail daemon from accessing or modifying them, which results in complete service disruption.
The technical flaw manifests through improper file locking implementation within the Sendmail application. When the mail server attempts to access any of these four file types, it expects to acquire shared or exclusive locks to ensure data consistency and prevent concurrent access issues. However, the vulnerable versions contain a race condition or flawed locking logic that allows local users to establish exclusive locks on these critical files. This design flaw creates a scenario where legitimate mail server operations cannot proceed, as the daemon becomes unable to perform its core functions of processing mail queues, maintaining aliases, updating statistics, or managing process identification information.
The operational impact of this vulnerability extends beyond simple service interruption to create complete mail service failures that can severely impact organizational communication infrastructure. When local users successfully lock these files, the Sendmail daemon enters a state where it cannot process incoming or outgoing mail, leading to message queuing failures and complete service unavailability. The vulnerability is particularly concerning because it only requires local user access, meaning that any user with system-level privileges or compromised local accounts can trigger the denial of service condition. This makes the attack surface relatively broad and the potential for exploitation significant in environments where local access is not properly restricted.
From a cybersecurity perspective, this vulnerability aligns with CWE-661, which describes insufficient locking mechanisms, and represents a classic example of a resource exhaustion attack. The ATT&CK framework categorizes this under privilege escalation and denial of service techniques, as local users can leverage this weakness to gain control over system resources and disrupt critical services. Organizations running vulnerable Sendmail versions face substantial risk, particularly in environments where local account security is not adequately enforced. The vulnerability also demonstrates poor adherence to secure coding practices regarding resource management and concurrent access control. Mitigation strategies should include immediate patching to versions beyond 8.12.3, implementation of proper file access controls, and monitoring for unauthorized local file access patterns. System administrators should also consider restricting local user privileges and implementing robust process monitoring to detect and prevent exploitation attempts. The vulnerability underscores the importance of proper file locking mechanisms in server applications and highlights how seemingly minor implementation flaws can result in complete service disruption.