A flaw was found in the way Samba handled file/directory metadata. This flaw allows an authenticated attacker with permissions to read or modify share metadata, to perform this operation outside of the share.
https://www.samba.org/samba/security/CVE-2021-20316.html
https://security.gentoo.org/glsa/202309-06
https://security-tracker.debian.org/tracker/CVE-2021-20316
https://bugzilla.samba.org/show_bug.cgi?id=14842