CVE-2026-64388

Name	CVE-2026-64388
Description	In the Linux kernel, the following vulnerability has been resolved: smb/client: fix chown/chgrp with SMB3 POSIX Extensions Ownership (chown) and group (chgrp) modifications were being ignored when mounting with SMB3 POSIX Extensions unless CIFS_MOUNT_CIFS_ACL or CIFS_MOUNT_MODE_FROM_SID were also explicitly set. Fix this by checking for posix_extensions in cifs_setattr_nounix() when updating UID and GID, ensuring that id_mode_to_cifs_acl() is called to map and set the ownership/group information on the server.
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)

Vulnerable and fixed packages

The table below lists information on source packages.

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

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
linux	source	(unstable)	7.1.4-1

https://git.kernel.org/linus/760ef2c579c2609cf17fb1cd5392f64d42d43d33 (7.2-rc1)