CVE-2014-1453 in FreeBSD
Summary
by MITRE
The NFS server (nfsserver) in FreeBSD 8.3 through 10.0 does not acquire locks in the proper order when converting a directory file handle to a vnode, which allows remote authenticated users to cause a denial of service (deadlock) via vectors involving a thread that uses the correct locking order.
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Analysis
by VulDB Data Team • 05/11/2026
The vulnerability identified as CVE-2014-1453 affects the Network File System server implementation in FreeBSD versions ranging from 8.3 through 10.0. This issue represents a critical concurrency flaw within the kernel-level file system operations that govern how the NFS server manages directory file handles and vnode conversions. The problem manifests specifically when the system attempts to resolve directory file handles to their corresponding vnodes, which are fundamental data structures used by the FreeBSD kernel to represent file system objects in memory. The improper locking mechanism creates a condition where multiple threads attempting to access the same directory resources can become trapped in a deadlock scenario, effectively rendering the NFS service unavailable to legitimate users.
The technical root cause of this vulnerability stems from a violation of proper locking order protocols within the kernel's NFS implementation. When a directory file handle needs to be converted to a vnode, the system must acquire multiple locks in a specific sequence to maintain data consistency and prevent race conditions. However, the FreeBSD NFS server implementation fails to follow the correct locking hierarchy, creating opportunities for threads to acquire locks in an inconsistent order. This improper ordering allows for circular wait conditions where Thread A holds Lock X and waits for Lock Y, while Thread B holds Lock Y and waits for Lock X, resulting in a complete system deadlock. The vulnerability specifically impacts authenticated remote users who can exploit this condition through carefully crafted NFS operations that trigger the problematic code path involving directory handle resolution.
The operational impact of CVE-2014-1453 extends beyond simple service disruption to potentially compromise the stability and availability of networked file systems in FreeBSD environments. When a deadlock occurs within the NFS server, all NFS operations that depend on the affected directory structures become unresponsive, leading to cascading failures throughout the network infrastructure that relies on NFS for file sharing. This vulnerability affects systems where FreeBSD serves as an NFS server, particularly impacting enterprise environments that depend on centralized file storage solutions. The denial of service condition can persist until the system is manually restarted or until the specific deadlock scenario is resolved through kernel-level intervention, making it particularly dangerous in production environments where continuous availability is critical. Security researchers have classified this issue as a deadlock vulnerability that directly relates to CWE-362, which describes concurrent execution using shared resource access issues.
Mitigation strategies for CVE-2014-1453 primarily focus on immediate system updates and operational hardening measures. The most effective solution involves upgrading FreeBSD systems to versions that contain the patched NFS implementation, specifically those beyond the affected range of 8.3 through 10.0. System administrators should implement comprehensive patch management procedures to ensure all NFS server instances receive timely updates. Additionally, network segmentation and access controls can help limit the attack surface by restricting which authenticated users can interact with the NFS service. Monitoring solutions should be deployed to detect unusual patterns of NFS service behavior that might indicate a deadlock condition, enabling rapid response to potential exploitation attempts. The vulnerability also highlights the importance of proper kernel locking practices and adherence to established concurrency control methodologies, aligning with ATT&CK framework techniques that emphasize privilege escalation and denial of service through system resource manipulation. Organizations should conduct thorough testing of NFS configurations and implement proper resource limits to prevent exploitation attempts from overwhelming system resources during attempted attacks.