USN-5142-1: Samba vulnerabilities

Releases

• Ubuntu 21.10
• Ubuntu 21.04
• Ubuntu 20.04 LTS

Packages

• samba - SMB/CIFS file, print, and login server for Unix

Details

Stefan Metzmacher discovered that Samba incorrectly handled SMB1 client
connections. A remote attacker could possibly use this issue to downgrade
connections to plaintext authentication. (CVE-2016-2124)

Andrew Bartlett discovered that Samba incorrectly mapping domain users to
local users. An authenticated attacker could possibly use this issue to
become root on domain members. (CVE-2020-25717)

Andrew Bartlett discovered that Samba did not correctly sandbox Kerberos
tickets issues by an RODC. An RODC could print administrator tickets,
contrary to expectations. (CVE-2020-25718)

Andrew Bartlett discovered that Samba incorrectly handled Kerberos tickets.
Delegated administrators could possibly use this issue to impersonate
accounts, leading to total domain compromise. (CVE-2020-25719)

Andrew Bartlett discovered that Samba did not provide stable AD
identifiers to Kerberos acceptors. (CVE-2020-25721)

Andrew Bartlett discovered that Samba did not properly check sensitive
attributes. An authenticated attacker could possibly use this issue to
escalate privileges. (CVE-2020-25722)

Stefan Metzmacher discovered that Samba incorrectly handled certain large
DCE/RPC requests. A remote attacker could possibly use this issue to
bypass signature requirements. (CVE-2021-23192)

William Ross discovered that Samba incorrectly handled memory. A remote
attacker could use this issue to cause Samba to crash, resulting in a
denial of service, or possibly escalate privileges. (CVE-2021-3738)

Joseph Sutton discovered that Samba incorrectly handled certain TGS
requests. An authenticated attacker could possibly use this issue to cause
Samba to crash, resulting in a denial of service. (CVE-2021-3671)

The fix for CVE-2020-25717 results in possible behaviour changes that could
affect certain environments. Please see the upstream advisory for more
information:

https://www.samba.org/samba/security/CVE-2020-25717.html

Update instructions

The problem can be corrected by updating your system to the following package versions:

Ubuntu 21.10

• samba - 2:4.13.14+dfsg-0ubuntu0.21.10.1

Ubuntu 21.04

• samba - 2:4.13.14+dfsg-0ubuntu0.21.04.1

Ubuntu 20.04

• samba - 2:4.13.14+dfsg-0ubuntu0.20.04.1

This update uses a new upstream release, which includes additional bug
fixes. In general, a standard system update will make all the necessary
changes.

References

• CVE-2020-25721
• CVE-2021-3738
• CVE-2020-25717
• CVE-2016-2124
• CVE-2020-25722
• CVE-2021-3671
• CVE-2020-25719
• CVE-2021-23192
• CVE-2020-25718

Related notices

• USN-5174-1: winbind, smbclient, samba-dev, registry-tools, samba-dsdb-modules, samba-common-bin, libnss-winbind, python-samba, libparse-pidl-perl, samba-testsuite, samba, samba-libs, samba-common, libwbclient-dev, ctdb, libsmbclient, libsmbclient-dev, samba-vfs-modules, libpam-winbind, libwbclient0
• USN-5675-1: libgssapi3-heimdal, libheimntlm0-heimdal, libasn1-8-heimdal, heimdal-clients-x, libkdc2-heimdal, heimdal, libheimbase1-heimdal, libkadm5srv8-heimdal, libkafs0-heimdal, libhcrypto4-heimdal, heimdal-multidev, libsl0-heimdal, heimdal-clients, heimdal-docs, heimdal-servers, libkrb5-26-heimdal, heimdal-kdc, libhx509-5-heimdal, heimdal-kcm, heimdal-servers-x, libroken18-heimdal, heimdal-dev, libhdb9-heimdal, libwind0-heimdal, libotp0-heimdal, libkadm5clnt7-heimdal