Published: 31 January 2022
All versions of Samba prior to 4.15.5 are vulnerable to a malicious client using a server symlink to determine if a file or directory exists in an area of the server file system not exported under the share definition. SMB1 with unix extensions has to be enabled in order for this attack to succeed.
per upstream, fixing this required a whole rewrite of the VFS layer and there is no reasonable way to fix this in versions older than 4.15.x. Marking this CVE as ignored for older releases.
This issue can be mitigated by disabling SMB1, which is the default configuration in Samba 4.11 and above. In environments where SMB1 cannot be disabled, symlink support can be disabled with unix extensions = no.
Severity score breakdown