A flaw was found in Samba’s handling of NTFS-style reparse points on shares configured with read only = yes. Due to missing SMB-layer access checks, authenticated users with underlying filesystem write permissions may create or delete reparse point metadata through SMB operations even on read-only exports. This could allow modification of SMB-visible file behavior, including converting files into symbolic links or other reparse point types.
Administrators can mitigate this issue by ensuring users who access a read only = yes Samba share do not have filesystem-level write permission to the exported files.
A server administrator may also monitor and remove unintended "user.SmbReparse" xattr (extended attributes) and the associated FILE_ATTRIBUTE_REPARSE_POINT "user.DosAttrib" bit metadata if exploitation is suspected.