Debian Security Advisory

DSA-5003-1 samba -- security update

Date Reported:
09 Nov 2021
Affected Packages:
Security database references:
In Mitre's CVE dictionary: CVE-2016-2124, CVE-2020-25717, CVE-2020-25718, CVE-2020-25719, CVE-2020-25721, CVE-2020-25722, CVE-2021-3738, CVE-2021-23192.
More information:

Several vulnerabilities have been discovered in Samba, a SMB/CIFS file, print, and login server for Unix.

  • CVE-2016-2124

    Stefan Metzmacher reported that SMB1 client connections can be downgraded to plaintext authentication.

  • CVE-2020-25717

    Andrew Bartlett reported that Samba may map domain users to local users in an undesired way, allowing for privilege escalation. The update introduces a new parameter min domain uid (default to 1000) to not accept a UNIX uid below this value.

  • CVE-2020-25718

    Andrew Bartlett reported that Samba as AD DC, when joined by an RODC, did not confirm if the RODC was allowed to print a ticket for that user, allowing an RODC to print administrator tickets.

  • CVE-2020-25719

    Andrew Bartlett reported that Samba as AD DC, did not always rely on the SID and PAC in Kerberos tickets and could be confused about the user a ticket represents. If a privileged account was attacked this could lead to total domain compromise.

  • CVE-2020-25721

    Andrew Bartlett reported that Samba as a AD DC did not provide a way for Linux applications to obtain a reliable SID (and samAccountName) in issued tickets.

  • CVE-2020-25722

    Andrew Bartlett reported that Samba as AD DC did not do sufficient access and conformance checking of data stored, potentially allowing total domain compromise.

  • CVE-2021-3738

    William Ross reported that the Samba AD DC RPC server can use memory that was free'd when a sub-connection is closed, resulting in denial of service, and potentially, escalation of privileges.

  • CVE-2021-23192

    Stefan Metzmacher reported that if a client to a Samba server sent a very large DCE/RPC request, and chose to fragment it, an attacker could replace later fragments with their own data, bypassing the signature requirements.

For the stable distribution (bullseye), these problems have been fixed in version 2:4.13.13+dfsg-1~deb11u2.

We recommend that you upgrade your samba packages.

For the detailed security status of samba please refer to its security tracker page at: