CVE-1999-1564 in FreeBSD
Summary
by MITRE
FreeBSD 3.2 and possibly other versions allows a local user to cause a denial of service (panic) with a large number accesses of an NFS v3 mounted directory from a large number of processes.
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Analysis
by VulDB Data Team • 04/19/2026
This vulnerability exists in FreeBSD version 3.2 and potentially other releases where a local user can trigger a system panic through excessive concurrent access to an NFSv3 mounted directory. The flaw manifests when multiple processes simultaneously attempt to access the same NFSv3 mounted filesystem, leading to resource exhaustion and system instability. The vulnerability stems from inadequate synchronization mechanisms within the kernel's handling of concurrent file operations on NFS mounts, particularly in the context of high process concurrency. This represents a classic denial of service scenario where legitimate system resources become consumed or corrupted through excessive concurrent access patterns.
The technical implementation of this vulnerability involves the kernel's handling of file system operations in the Network File System version 3 implementation. When numerous processes attempt to access the same NFSv3 mounted directory concurrently, the system's internal data structures and locking mechanisms become overwhelmed. This typically occurs during operations such as directory traversal, file listing, or concurrent file access patterns that cause the kernel to panic. The vulnerability is classified as a local privilege escalation issue since it requires local system access but can result in system-wide denial of service conditions. From a cybersecurity perspective, this vulnerability aligns with CWE-400, which addresses unchecked resource consumption, and represents a system stability threat rather than a direct security breach.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromising the entire system's availability. A malicious local user could exploit this weakness to repeatedly trigger system panics, effectively making the system unusable until manual reboot or system recovery is performed. The vulnerability affects systems running FreeBSD 3.2 and potentially other versions that share the same NFSv3 implementation, making it particularly concerning for networked environments where multiple users might have local access to systems with NFS mounts. This issue demonstrates the importance of proper resource management and concurrency control in kernel-level file system implementations.
Mitigation strategies for this vulnerability include applying the appropriate FreeBSD security patches that address the specific NFSv3 concurrency issues in the kernel's file system handling code. System administrators should also consider implementing process limits and resource controls to prevent excessive concurrent access to NFS mounts. Additionally, monitoring systems should be deployed to detect unusual patterns of concurrent NFS access that might indicate exploitation attempts. The ATT&CK framework categorizes this vulnerability under privilege escalation and denial of service techniques, where adversaries leverage system weaknesses to disrupt operations. Organizations should ensure their FreeBSD systems are maintained with current security updates and implement proper access controls to limit local user capabilities that could exploit such kernel-level weaknesses.