This is Debian bug #584104, which we tagged as release critical: As of version 2:4.5-1, mount.cifs appears to ignore the presence of the 'credentials' option given in the command line: sham@sham-desktop:/tmp$ sudo mount.cifs -o credentials=/etc/auto.smb.gibson //gibson/sham foo Password: This ends up impacting on autofs as well, as smb/cifs shares are no longer automountable. I can confirm that downgrading cifs-utils and smbfs to the previous package version (2:4.1-1) makes this problem go away.
Patch for this is already in git: http://git.samba.org/?p=cifs-utils.git;a=commit;h=d3743bbfd82b058b68c1bcf6e3341966a3d9f707 It should make the 4.6 release.