CVE-2026-64395
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: require source read access for duplicate extents
FSCTL_DUPLICATE_EXTENTS_TO_FILE passes the source file directly to
vfs_clone_file_range() or vfs_copy_file_range() without checking the SMB
access mask granted to the source handle. A handle opened with attribute
access can consequently be used to copy file contents into an
attacker-readable destination.
Require FILE_READ_DATA on the source handle before either VFS operation,
matching other ksmbd data-copy paths.
CSIRTS triage
- What
- The ksmbd server requires source read access for duplicate extents to prevent unauthorized access.
- Who is affected
- Deployments using the ksmbd SMB server.
- Urgency
- Remediation is necessary to ensure proper access controls, with no known exploits at this time.
- Action
- Update the ksmbd server to the latest version.
AI-assisted analysis generated from the source advisory — verify against the original.
⚡ Watch CVE-2026-64395
Get an email if CVE-2026-64395 is added to CISA KEV, gains public exploit code, or a new advisory cites it — max one per day, one-click unsubscribe.
Exploitation outlook
- Low exploitation risk0.41% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 33% of all EPSS-scored CVEs.
Advisory coverage (2)
External references
Embed the live status
— this badge updates automatically when the KEV or exploit status changes. How to embed it →
[](https://www.csirts.com/cve/CVE-2026-64395)