CVE-2026-64399

Name	CVE-2026-64399
Description	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.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
References	DLA-4720-1, DLA-4723-1, DLA-4724-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
linux (PTS)	bullseye	5.10.223-1	fixed
	bullseye (security)	5.10.262-1	fixed
	bookworm	6.1.176-1	vulnerable
	bookworm (security)	6.1.180-1	fixed
	trixie	6.12.94-1	vulnerable
	trixie (security)	6.12.101-1	fixed
	forky	7.1.7-1	fixed
	sid	7.1.8-1	fixed
linux-6.1 (PTS)	bullseye (security)	6.1.180-1~deb11u1	fixed
linux-6.12 (PTS)	bookworm (security)	6.12.100-1~deb12u1	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Origin
linux	source	bullseye	(not affected)
linux	source	bookworm	6.1.180-1	DLA-4720-1
linux	source	trixie	6.12.96-1
linux	source	(unstable)	7.1.4-1
linux-6.1	source	bullseye	6.1.180-1~deb11u1	DLA-4723-1
linux-6.12	source	bookworm	6.12.100-1~deb12u1	DLA-4724-1

[bullseye] - linux <not-affected> (Vulnerable code not present)
https://git.kernel.org/linus/388e4139db27a9e3612c9d356b826f5b1ff6a9e3 (7.2-rc1)