CVE-2008-3676 in hMailServer
Summary
by MITRE
Unspecified vulnerability in the IMAP server in hMailServer 4.4.1 allows remote authenticated users to cause a denial of service (resource exhaustion or daemon crash) via a long series of IMAP commands.
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Analysis
by VulDB Data Team • 12/29/2025
The vulnerability identified as CVE-2008-3676 resides within the IMAP server component of hMailServer version 4.4.1, representing a critical security flaw that enables remote authenticated attackers to execute denial of service attacks against the mail server infrastructure. This issue manifests when legitimate users who have successfully authenticated to the system can exploit a design weakness in the IMAP protocol implementation that leads to resource exhaustion or complete daemon crashes. The vulnerability specifically targets the server's handling of IMAP command sequences, where an attacker can submit an extended series of carefully crafted commands that overwhelm the server's processing capabilities and memory resources.
From a technical perspective, this vulnerability operates as a resource exhaustion attack that leverages the IMAP server's insufficient input validation and command processing mechanisms. The flaw occurs during the parsing and execution of IMAP commands where the server fails to properly limit the number of commands that can be processed in a single session or detect when command sequences become excessively long. This represents a classic example of inadequate input sanitization and lack of proper rate limiting or command sequence validation. The vulnerability falls under the CWE-400 category of "Uncontrolled Resource Consumption" and specifically relates to CWE-770 which addresses allocation of resources without proper limits or checks. The attack vector requires authentication, meaning that only users with valid credentials can exploit this weakness, but this authentication requirement does not make the vulnerability any less dangerous as it can still be leveraged by compromised accounts or insider threats.
The operational impact of CVE-2008-3676 extends beyond simple service disruption to potentially compromise the entire mail server infrastructure and affect business continuity for organizations relying on hMailServer for their email communications. When exploited, the vulnerability can cause the IMAP daemon to consume excessive system resources such as memory and CPU cycles, leading to system instability, application crashes, and complete service unavailability. The resource exhaustion can manifest as memory leaks, thread starvation, or process crashes that require manual intervention to restore normal operations. Organizations using hMailServer in production environments may experience significant downtime, email delivery failures, and potential data loss during the period when the service is unavailable. The impact is particularly severe in environments where email services are critical for business operations, as this vulnerability can effectively shut down email communications for entire user bases.
Mitigation strategies for CVE-2008-3676 should focus on both immediate patching and operational hardening measures. The primary solution involves upgrading to a patched version of hMailServer that addresses the IMAP command processing flaw and implements proper input validation and resource limiting mechanisms. Organizations should also implement monitoring and alerting systems to detect unusual command patterns or resource consumption spikes that may indicate exploitation attempts. Network-level protections such as implementing rate limiting, connection throttling, and command sequence validation can provide additional defense in depth. From an ATT&CK framework perspective, this vulnerability aligns with techniques categorized under T1499.004 "Endpoint Denial of Service" and T1566.002 "Phishing" as it can be exploited through authenticated access that may be gained through social engineering or credential compromise. Administrators should also consider implementing intrusion detection systems that can identify and block suspicious command sequences, while maintaining regular backups and disaster recovery procedures to minimize downtime during potential exploitation events.