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
How to mitigate CVE-2026-64400
Install security update from vendor's repository.
Linux kernel - update to 7.0 rc3