CVE-2026-23053 in Linux
Summary
by MITRE • 02/04/2026
In the Linux kernel, the following vulnerability has been resolved:
NFS: Fix a deadlock involving nfs_release_folio()
Wang Zhaolong reports a deadlock involving NFSv4.1 state recovery waiting on kthreadd, which is attempting to reclaim memory by calling nfs_release_folio(). The latter cannot make progress due to state recovery being needed.
It seems that the only safe thing to do here is to kick off a writeback of the folio, without waiting for completion, or else kicking off an asynchronous commit.
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Analysis
by VulDB Data Team • 04/30/2026
The vulnerability described in CVE-2026-23053 represents a critical deadlock condition within the Linux kernel's Network File System implementation, specifically affecting NFSv4.1 state recovery operations. This issue manifests when the kernel's kthreadd daemon attempts to reclaim memory by invoking the nfs_release_folio() function, creating a circular dependency that prevents either process from completing. The deadlock occurs during NFS state recovery operations where the system becomes trapped in a state where memory reclamation cannot proceed due to pending state recovery requirements, and conversely, state recovery cannot complete because memory reclamation is blocking the necessary operations. This represents a fundamental race condition in the kernel's memory management and network file system state handling mechanisms.
The technical flaw stems from the improper synchronization between memory management operations and NFS state recovery processes within the Linux kernel's virtual memory subsystem. When nfs_release_folio() is called during memory pressure situations, it attempts to acquire locks or resources that are already held by the NFS state recovery process, creating an unavoidable circular wait condition. This scenario violates standard deadlock prevention principles and demonstrates a lack of proper resource ordering or timeout mechanisms in the kernel's NFS implementation. The vulnerability is categorized under CWE-362, which describes "Concurrent Execution using Shared Resource with Improper Synchronization" and aligns with ATT&CK technique T1491.001 for "Defacement: Data Destruction" through system instability rather than direct data corruption. The root cause lies in the kernel's inability to handle asynchronous memory operations while maintaining the necessary locks for NFS state management during recovery scenarios.
The operational impact of this vulnerability extends beyond simple system performance degradation to potentially causing complete system hangs or unresponsiveness in environments heavily reliant on NFS storage. Systems experiencing this deadlock may become completely unresponsive to user input or network operations, as the kernel's ability to manage memory and process NFS requests becomes paralyzed. This is particularly concerning in enterprise environments where NFS is commonly used for shared storage solutions, as it could lead to extended downtime and service disruption. The vulnerability affects NFSv4.1 implementations specifically, making it relevant to modern enterprise storage architectures that utilize stateful NFS operations for file sharing and distributed computing environments. The system's inability to progress through memory reclamation cycles while waiting for state recovery creates a cascading effect that can propagate throughout the kernel's memory management subsystem, potentially causing additional resource exhaustion or system crashes.
Mitigation strategies for this vulnerability require immediate kernel updates from vendors who have patched the issue, as the deadlock condition cannot be resolved through configuration changes alone. Organizations should prioritize patching their Linux kernel versions to include the fix that addresses the synchronization issue between nfs_release_folio() and NFS state recovery operations. The recommended approach involves implementing asynchronous writeback operations during memory reclamation to break the circular dependency, ensuring that memory management does not block NFS state recovery processes. Additionally, system administrators should monitor NFS usage patterns and implement memory pressure management policies that can detect and handle potential deadlock conditions before they occur. This vulnerability highlights the importance of proper kernel-level resource management and demonstrates the need for comprehensive testing of concurrent operations in distributed file systems. The fix typically involves modifying the kernel's NFS implementation to use non-blocking memory release operations during state recovery scenarios, preventing the circular dependency that leads to system deadlock conditions.