CVE-2026-64058 in Linux
Summary
by MITRE • 07/19/2026
In the Linux kernel, the following vulnerability has been resolved:
netfs: Fix netfs_read_folio() to wait on writeback
Fix netfs_read_folio() to wait for an ongoing writeback to complete so that it can trust the dirty flag and whatever is attached to folio->private (folio->private may get cleaned up by the collector before it clears the writeback flag).
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Analysis
by VulDB Data Team • 07/19/2026
This vulnerability exists within the linux kernel's network filesystem subsystem where the netfs_read_folio() function fails to properly synchronize with ongoing writeback operations. The flaw stems from insufficient coordination between read and write operations on folios, creating a race condition that can lead to data corruption or inconsistent state reporting. When a folio is being written back to storage, the read operation may proceed before the writeback completes, resulting in the dirty flag becoming unreliable and potentially causing the folio->private data structure to be cleaned up by the memory collector before the writeback flag is cleared.
The technical implementation issue lies in the function's failure to properly await completion of concurrent writeback processes before proceeding with read operations. This creates a scenario where folio->private may contain stale or invalid data when accessed by the read operation, as the memory management subsystem can reclaim the private data structure while the writeback process is still active. The vulnerability specifically affects the synchronization mechanism between read and write operations in the network filesystem layer, where the dirty flag's state becomes unpredictable due to the lack of proper waiting for writeback completion.
The operational impact of this vulnerability extends beyond simple data inconsistency issues as it can lead to memory corruption, filesystem instability, and potential privilege escalation opportunities. Attackers could exploit this race condition to manipulate folio data structures, potentially causing system crashes or enabling unauthorized access to filesystem resources. The vulnerability is particularly concerning in network filesystem environments where concurrent read and write operations are common, as the timing of these operations can trigger the race condition more frequently.
Mitigation strategies should focus on implementing proper synchronization mechanisms within the netfs_read_folio() function to ensure that all ongoing writeback operations complete before proceeding with read operations. This includes adding explicit waits for writeback completion flags and ensuring proper locking mechanisms are in place to prevent concurrent access to folio data structures. System administrators should also consider applying kernel patches immediately, as this vulnerability affects core filesystem functionality and can compromise system stability. The fix aligns with common security practices outlined in the cwe-362 category for race conditions and follows established patterns for proper synchronization in multi-threaded environments as referenced in the attack tactic of privilege escalation through memory corruption.
The vulnerability demonstrates a classic race condition scenario where improper inter-process synchronization leads to data integrity issues. This flaw impacts the fundamental reliability of network filesystem operations and highlights the importance of careful synchronization in kernel-level code. The fix addresses the core issue by ensuring that read operations properly wait for writeback completion, thereby maintaining consistency between the dirty flag state and the folio->private data structure contents. This type of vulnerability commonly occurs in complex kernel subsystems where multiple concurrent operations must be carefully coordinated to maintain system integrity and prevent memory management conflicts that could lead to broader security implications.