ksmbd: add permission checks for FSCTL_DUPLICATE_EXTENTS_TO_FILE
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA.
Summary
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 handle overwrote the file's data via the clone. Add both checks, matching the FSCTL_SET_SPARSE permission fix; require FILE_WRITE_DATA since this writes data.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Linux | Linux | 5.15 and later | 6.1.178, 6.6.145, 6.12.96, 6.18.39, 7.1.4, 7.2 | Patch available | CNA |
- Linux VendorLinux Affected 5.15 and later Fixed in 6.1.178, 6.6.145, 6.12.96, 6.18.39, 7.1.4, 7.2 Patch available CNA
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | 5.15 to before 6.1.178; 6.2 to before 6.6.145; 6.7 to before 6.12.96; 6.13 to before 6.18.39; 6.19 to before 7.1.4 | Vulnerable | Linux |
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions 5.15 to before 6.1.178; 6.2 to before 6.6.145; 6.7 to before 6.12.96; 6.13 to before 6.18.39; 6.19 to before 7.1.4 Vulnerable ·Linux
Remediation
- Fix · CNA Linux (Linux) Fixed in 6.1.178, 6.6.145, 6.12.96, 6.18.39, 7.1.4, 7.2
Vendor assessments
Red Hat
Red Hat rating: Important. Red Hat's page for this CVE →
Not affected: 5 products
- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
Timeline
- 2026-10-02 Threatist record created from CVE-2026-64399
- 2026-10-03 Alias added: GHSA-mrp6-592v-c3fh
- 2026-10-16 EPSS moved to the below the 50th percentile
- 2026-10-20 Affected versions changed · Red Hat
References
Patch 6
- https://git.kernel.org/stable/c/bf460ad5958d506492de4524a656439da3f99c51
- https://git.kernel.org/stable/c/620d133d469295ee7c017ca6aafac335f65c4a5a
- https://git.kernel.org/stable/c/9b9cf7e65cbeaae1b6636144bacee611cdd7a5d6
- https://git.kernel.org/stable/c/baae7b39673ec21073a25e3d14f8feaada01d5df
- https://git.kernel.org/stable/c/c917e4522d251071dde9871b9142d8ea1186ebfe
- https://git.kernel.org/stable/c/388e4139db27a9e3612c9d356b826f5b1ff6a9e3
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Sources
- CVE-2026-64399 · CVE Program
- CVE-2026-64399 · NVD
- FIRST EPSS
- GHSA-mrp6-592v-c3fh · GitHub Advisory Database · CC BY 4.0
- CVE-2026-64399 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences