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USN-5142-1: Samba vulnerabilities

11 November 2021

Several security issues were fixed in Samba.

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Releases

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

Reduce your security exposure

Ubuntu Pro provides ten-year security coverage to 25,000+ packages in Main and Universe repositories, and it is free for up to five machines.

Learn more about Ubuntu Pro

Update instructions

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

Ubuntu 21.10
Ubuntu 21.04
Ubuntu 20.04

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

Related notices

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