CVE-1999-0831 in Linux
Summary
by MITRE
Denial of service in Linux syslogd via a large number of connections.
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Analysis
by VulDB Data Team • 04/19/2026
The vulnerability identified as CVE-1999-0831 represents a critical denial of service weakness in the Linux syslogd daemon that was prevalent during the late 1990s era of system administration. This flaw specifically targeted the syslogd service which serves as the central logging facility for Unix and Linux systems, responsible for receiving, processing, and storing system log messages from various sources throughout the network infrastructure. The vulnerability emerged from the daemon's inadequate handling of connection management and resource allocation when faced with an excessive volume of concurrent connection attempts, creating a scenario where legitimate system operations could be severely disrupted.
The technical root cause of this vulnerability stems from the syslogd daemon's insufficient validation and management of incoming network connections, particularly when multiple simultaneous connection requests are received from the same or different sources. This weakness creates a condition where the system's logging infrastructure becomes overwhelmed by connection attempts, leading to resource exhaustion and ultimately causing the service to become unresponsive or crash entirely. The flaw operates at the application layer of the network stack, specifically affecting the syslog protocol implementation that governs how system messages are transmitted and received across networked environments. This vulnerability aligns with CWE-400 which categorizes improper resource shutdown or release issues, and more specifically with CWE-1333 which addresses resource exhaustion in network services.
The operational impact of CVE-1999-0831 extends far beyond simple service disruption, as it fundamentally compromises the integrity of system monitoring and security operations within affected environments. When the syslogd daemon becomes unresponsive due to connection flooding, system administrators lose critical visibility into system activities, security events, and operational anomalies that would normally be logged for forensic analysis and real-time monitoring. This creates a dangerous situation where malicious actors could exploit this vulnerability to perform coordinated denial of service attacks against system logging capabilities, effectively creating a blind spot in security infrastructure. The vulnerability also impacts the broader system stability since many security tools and monitoring systems depend on the availability of syslog services for proper operation, potentially leading to cascading failures throughout the network infrastructure. From an ATT&CK framework perspective, this vulnerability maps to technique T1499.004 which covers network denial of service attacks, and T1070.002 which involves the use of system logs for information gathering and evasion.
Mitigation strategies for this vulnerability require a multi-layered approach that addresses both immediate protection and long-term system hardening. System administrators should implement connection rate limiting and maximum connection thresholds within the syslogd configuration to prevent resource exhaustion from excessive connection attempts. Network-level firewalls and intrusion prevention systems should be configured to monitor and filter suspicious connection patterns that could indicate exploitation attempts. Regular system updates and patches are essential as the vulnerability was addressed in subsequent releases of the syslogd daemon through improved connection handling and resource management. Additionally, implementing redundant logging solutions and distributed logging architectures can provide failover capabilities when primary syslog services become unavailable. The vulnerability also highlights the importance of network segmentation and access control measures that limit the sources from which syslog connections can be initiated, reducing the attack surface and potential impact of such exploits. Organizations should also establish monitoring protocols that can detect unusual connection patterns and automatically trigger alerts when connection thresholds are approached, enabling proactive response to potential exploitation attempts.