Improper locking in Linux kernel - CVE-2026-64062

Vulnerability identifier: #VU138580

CSH Severity: Low

CVSS v4: 6.8 [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]

CVE-ID: CVE-2026-64062

CWE-ID: CWE-667

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to cause a denial of service.

The vulnerability exists due to improper lock handling in netfs_advance_writethrough() when processing write-through operations on folios. A local user can trigger write-through activity to cause a deadlock and deny service.

The issue involves interaction with mmapped reads and writes during folio writeback handling.

Linux kernel
Ubuntu
linux-ibm (Ubuntu package)
linux-azure (Ubuntu package)
linux-aws (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-nvidia-bos (Ubuntu package)

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux-ibm (Ubuntu package) - addressed in versions 7.0.0-1008.8, 7.0.0-1010.10
linux-azure (Ubuntu package) - addressed in versions 7.0.0-1009.9, 7.0.0-1010.10
linux-aws (Ubuntu package) - addressed in versions 7.0.0-1009.9, 7.0.0-1015.15
linux-nvidia (Ubuntu package) - addressed in versions 7.0.0-1016.16, 7.0.0-1016.16~24.04.1
linux-nvidia-bos (Ubuntu package) - update to 7.0.0-2016.16

• https://git.kernel.org/stable/c/003aa0dd26c964025acd6d1213bcdbd674db2ca9
• https://git.kernel.org/stable/c/1468f39243ccb155b6d97f9a9932f610d1205d75
• https://git.kernel.org/stable/c/b6a4ae1634b3ad2aaa05222e53d36da532852faf
• https://git.kernel.org/stable/c/e40e9cbf3ee4d30ee9a97bd128c85500b6ad0da1

• Improper locking in Linux kernel netfs
• Ubuntu update for linux-ibm
• Ubuntu update for linux-azure
• Ubuntu update for linux-aws
• Ubuntu update for linux-nvidia-bos
• Ubuntu update for linux-nvidia