CVE-2026-64156
Received Received - Intake

Linux Kernel Write Skipping Vulnerability in netfs and afs

Publication date: 2026-07-19

Last updated on: 2026-07-19

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: netfs, afs: Fix write skipping in dir/link writepages Fix netfs_write_single() and afs_single_writepages() to better handle a write that would be skipped due to lock contention and WB_SYNC_NONE by returning 1 from netfs_write_single() if it skipped and making afs_single_writepages() skip also. If a skip occurs, the inode must be re-marked as the VFS may have cleared the mark. This is really only theoretical for directories in netfs_write_single() as the only path to that is through afs_single_writepages() that takes the ->validate_lock around it, thereby serialising it.

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Meta Information

Published
2026-07-19
Last Modified
2026-07-19
Generated
2026-07-20
AI Q&A
2026-07-19
EPSS Evaluated
N/A
NVD
CVE-2026-64156
EUVD
EUVD-2026-45841

Affected Vendors & Products

Currently, no data is known.

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel affects the netfs and AFS (Andrew File System) components. It involves a flaw in handling write operations during directory and link writepages. When a write is skipped due to lock contention and the WB_SYNC_NONE flag, the functions netfs_write_single() and afs_single_writepages() do not properly handle the skip condition. This can lead to the inode being incorrectly marked, potentially causing data inconsistencies.

Detection Guidance

This vulnerability is specific to the Linux kernel's netfs and AFS (Andrew File System) components. Detection requires checking kernel logs for writepage errors or skipped writes in these subsystems. Use commands like dmesg | grep -i 'netfs\|afs' or journalctl -k | grep -i 'writepage\|skip' to identify related errors.

Impact Analysis

The impact is primarily on systems using the Linux kernel with AFS or netfs. It may cause write operations to fail or behave unexpectedly, leading to potential data corruption or loss. However, the issue is noted as theoretical for directories due to existing serialization mechanisms.

Mitigation Strategies

Apply the latest kernel patches from your Linux distribution to resolve the issue. If immediate patching is not possible, monitor for symptoms like write failures or data corruption in AFS or netfs operations. Restart affected services after patching.

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