CVE-2026-64399 remediation guide

Linux

In the Linux kernel, the following vulnerability has been resolved: ksmbd: add permission checks for FSCTL_DUPLICATE_EXTENTS_TO_FILE The FSCTL_DUPLICATE_EXTENTS_TO_FILE arm of smb2_ioctl() overwrites the destination file's data via vfs_clone_file_range() with neither the share-level KSMBD_TREE_CONN_FLAG_WRITABLE check nor a per-handle fp->daccess check that the other write-bearing arms carry. A client can overwrite destination data on a read-only share, or from a handle opened with only FILE_WRITE_ATTRIBUTES (which still yields an FMODE_WRITE filp). FILE_WRITE_ATTRIBUTES-only destination ha...

Open CVE record

Research in progress

A verified fixed-version field is not available. Use the linked NVD and supporting references, then confirm the vendor-supported path before changing production systems.

ProductLinux

Affected versions>= eb817368f50c1cbe1bd07044124aad7db6330e3a < bf460ad5958d506492de4524a656439da3f99c51, >= eb817368f50c1cbe1bd07044124aad7db6330e3a < 620d133d469295ee7c017ca6aafac335f65c4a5a, >= eb817368f50c1cbe1bd07044124aad7db6330e3a < 9b9cf7e65cbeaae1b6636144bacee611cdd7a5d6, >= eb817368f50c1cbe1bd07044124aad7db6330e3a < baae7b39673ec21073a25e3d14f8feaada01d5df, >= eb817368f50c1cbe1bd07044124aad7db6330e3a < c917e4522d251071dde9871b9142d8ea1186ebfe, >= eb817368f50c1cbe1bd07044124aad7db6330e3a < 388e4139db27a9e3612c9d356b826f5b1ff6a9e3, >= 5.15

Fixed versionsNo verified fixed-version field is available yet

Priority basisReview · CVSS 9.8 · EPSS -

Identify the affected asset

Confirm whether Linux is installed, record the deployed version and installation path, and identify exposed interfaces.

Record the product name, package or appliance identifier, and installed version.
Identify internet-facing, administrative, API, and internal access paths.
Preserve the pre-change configuration and relevant service logs.

Validate the affected-version match

Compare the deployed version with the affected range: >= eb817368f50c1cbe1bd07044124aad7db6330e3a < bf460ad5958d506492de4524a656439da3f99c51, >= eb817368f50c1cbe1bd07044124aad7db6330e3a < 620d133d469295ee7c017ca6aafac335f65c4a5a, >= eb817368f50c1cbe1bd07044124aad7db6330e3a < 9b9cf7e65cbeaae1b6636144bacee611cdd7a5d6, >= eb817368f50c1cbe1bd07044124aad7db6330e3a < baae7b39673ec21073a25e3d14f8feaada01d5df, >= eb817368f50c1cbe1bd07044124aad7db6330e3a < c917e4522d251071dde9871b9142d8ea1186ebfe, >= eb817368f50c1cbe1bd07044124aad7db6330e3a < 388e4139db27a9e3612c9d356b826f5b1ff6a9e3, >= 5.15. Treat incomplete inventory results as unresolved.

Prioritize with independent signals

The CVSS severity warrants an early asset and exposure review. Combine this signal with asset criticality, exposure, compensating controls, and business impact.

Apply supported remediation

Follow the vendor advisory or supported update path. Current fixed-version status: No verified fixed-version field is available yet. Preserve configuration and rollback material before change.

Verify the result

Confirm the resulting version, service health, authentication and access paths, monitoring coverage, and relevant security logs.

Confirm the expected version and package state.
Run a functional health check for critical service paths.
Review authentication, error, application, and security monitoring logs.
Reassess exposure if the supported fix cannot be applied.

Operational boundary

This page does not replace the vendor advisory, support contract, change-management process, or recovery plan. Do not infer that an asset is unaffected from an incomplete inventory query or a missing fixed-version field.