Improper locking in Linux kernel - CVE-2026-64156
Published: July 20, 2026
Vulnerability identifier: #VU138475
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-64156
CWE-ID: CWE-667
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vendor: Linux Foundation
Affected software:
Linux kernel
Linux kernel
Detailed vulnerability description
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to improper lock handling in netfs_writeback_single() and afs_single_writepages() when processing writeback operations under lock contention with WB_SYNC_NONE. A local user can trigger writeback in a way that causes skipped writes to leave directory or link data improperly handled, resulting in a denial of service.
This issue is described as theoretical for directories because the afs_single_writepages() path serializes access with validate_lock.
How to mitigate CVE-2026-64156
Install security update from vendor's repository.