Path traversal in Linux kernel - CVE-2026-64400

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Main Vulnerability Database Vulnerabilities #VU139570

Path traversal in Linux kernel - CVE-2026-64400

Published: July 27, 2026


Vulnerability identifier: #VU139570
CSH Severity: Low
CVSS v4: 5.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-64400
CWE-ID: CWE-22
Exploitation vector: Remote access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote user to create files or directories outside the exported share.

The vulnerability exists due to improper limitation of a pathname to a restricted directory in __ksmbd_vfs_kern_path() when processing crafted paths with parent-directory components during caseless lookup retry. A remote user can send a specially crafted path to create files or directories outside the exported share.

The issue occurs because an -EXDEV error from path traversal detection is not handled before the caseless retry logic runs, and exploitation is limited to zero-length files or directories.


Affected software

Linux kernel
Debian Linux
Ubuntu
linux-nvidia-tegra (Ubuntu package)
linux (Ubuntu package)
linux-realtime (Ubuntu package)
linux-gcp (Ubuntu package)
linux-oracle (Ubuntu package)
linux-aws (Ubuntu package)
linux-raspi (Ubuntu package)
linux-azure (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-ibm (Ubuntu package)
linux-nvidia-bos (Ubuntu package)
linux-hwe-7.0 (Ubuntu package)
linux-gcp-7.0 (Ubuntu package)
linux-oracle-7.0 (Ubuntu package)
linux-azure-7.0 (Ubuntu package)
linux-oem-7.0 (Ubuntu package)
linux-gke (Ubuntu package)
linux-aws-7.0 (Ubuntu package)
linux-nvidia-7.0 (Ubuntu package)
linux (Debian package)

How to mitigate CVE-2026-64400

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux-nvidia-tegra (Ubuntu package) - update to 6.8.0-1035.38
linux (Ubuntu package) - update to 7.0.0-31.31
linux-realtime (Ubuntu package) - update to 7.0.0-31.31.1
linux-gcp (Ubuntu package) - update to 7.0.0-1011.11
linux-oracle (Ubuntu package) - update to 7.0.0-1011.11
linux-aws (Ubuntu package) - update to 7.0.0-1012.12
linux-raspi (Ubuntu package) - update to 7.0.0-1019.19
linux-azure (Ubuntu package) - update to 7.0.0-1014.14
linux-nvidia (Ubuntu package) - update to 7.0.0-1018.18
linux-ibm (Ubuntu package) - update to 7.0.0-1013.13
linux-nvidia-bos (Ubuntu package) - update to 7.0.0-2018.18
linux-hwe-7.0 (Ubuntu package) - update to 7.0.0-31.31~24.04.1
linux-gcp-7.0 (Ubuntu package) - update to 7.0.0-1011.11~24.04.1
linux-oracle-7.0 (Ubuntu package) - update to 7.0.0-1011.11~24.04.1
linux-azure-7.0 (Ubuntu package) - update to 7.0.0-1014.14~24.04.1
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1013.13
linux-gke (Ubuntu package) - update to 7.0.0-1006.7
linux-aws-7.0 (Ubuntu package) - update to 7.0.0-1012.12~24.04.1
linux-nvidia-7.0 (Ubuntu package) - update to 7.0.0-1018.18~24.04.1
linux (Debian package) - update to 6.12.115-2

External References

Related Security Bulletins