CVE-2000-0227 in Linux
Summary
by MITRE
The Linux 2.2.x kernel does not restrict the number of Unix domain sockets as defined by the wmem_max parameter, which allows local users to cause a denial of service by requesting a large number of sockets.
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Analysis
by VulDB Data Team • 04/21/2026
The vulnerability identified as CVE-2000-0227 represents a critical resource exhaustion flaw within the Linux 2.2.x kernel family that directly impacts system stability and availability. This issue stems from the kernel's insufficient enforcement of socket limits in the Unix domain socket implementation, creating a pathway for malicious local users to systematically deplete system resources through deliberate resource consumption. The vulnerability specifically targets the wmem_max parameter which governs the maximum send buffer size for sockets, yet fails to properly restrict the total number of Unix domain sockets that can be simultaneously created within the system. This oversight allows an attacker to continuously allocate new socket resources without adequate bounds checking, ultimately leading to system-wide resource exhaustion.
The technical exploitation of this vulnerability occurs through the systematic creation of Unix domain sockets, which are fundamental communication mechanisms used for inter-process communication within Unix-like systems. When a local user executes malicious code that repeatedly opens and maintains Unix domain sockets, the kernel allocates memory and system resources to manage each socket connection. The absence of proper socket count limits means that these resources accumulate without bounds, eventually consuming all available memory and system resources. The wmem_max parameter, which should regulate the maximum memory allocated for socket send buffers, does not extend its protective mechanism to limit the total number of socket instances that can be created. This creates a scenario where resource allocation becomes unbounded, leading to memory exhaustion and system instability.
From an operational perspective, this vulnerability presents a significant denial of service threat that can severely impact system availability and performance. The local nature of the attack means that any user with access to the system can potentially exploit this flaw, making it particularly dangerous in multi-user environments where privilege escalation might occur through other attack vectors. The impact extends beyond simple service disruption as the system may become unresponsive, crash, or require manual intervention to restore normal operations. System administrators face the challenge of identifying such attacks as they typically appear as resource exhaustion issues rather than obvious malicious activity, making detection more difficult. The vulnerability affects the core networking stack of the Linux kernel, meaning that all applications relying on Unix domain sockets for communication become vulnerable to this resource exhaustion attack.
Mitigation strategies for this vulnerability must address both immediate system protection and long-term architectural improvements to prevent similar issues. The most direct approach involves implementing proper socket count limits through kernel configuration parameters or system tuning mechanisms that can restrict the maximum number of Unix domain sockets that can be created. System administrators should also implement monitoring solutions that can detect unusual socket creation patterns and alert on potential resource exhaustion attacks. The implementation of resource limits through ulimit commands or systemd service configurations can help constrain socket allocation at the user level. Additionally, upgrading to newer kernel versions where this vulnerability has been addressed represents the most comprehensive solution, as later kernel releases include proper bounds checking and resource management for socket allocation. This vulnerability aligns with CWE-400 which categorizes resource exhaustion issues, and could be classified under ATT&CK technique T1499.001 for resource exhaustion attacks. The flaw demonstrates how seemingly minor configuration oversight in kernel networking components can lead to critical system stability issues, emphasizing the importance of comprehensive resource management in operating system design and the need for robust security testing of core system components.