Race condition in Linux kernel - CVE-2026-64065

Vulnerability identifier: #VU138565

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-2026-64065

CWE-ID: CWE-362

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 state management in netfs_write_begin() when handling write operations through the netfs and ceph write path. A local user can trigger the kernel BUG with crafted write activity to cause a denial of service.

The issue manifests as a VM_BUG_ON_FOLIO condition that can lead to an invalid opcode exception and kernel crash.

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/51ffb788f074c0a61953086f49008028c1e7b645
• https://git.kernel.org/stable/c/5ad05b6f5df296ef046589f222bb2587495b991e
• https://git.kernel.org/stable/c/b63971238beb79cf701dac33c6cefc56c07c89fa
• https://git.kernel.org/stable/c/dc7832d05deb4d632e8035e3299e31a3528fa0d0

• Race condition 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