A Samba security update has been released for Ubuntu Linux 18.04 LTS and 16.04 LTS.

USN-4510-1: Samba vulnerability

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Ubuntu Security Notice USN-4510-1
September 17, 2020

samba vulnerability
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS

Summary:

Samba would allow unintended access to files over the network.

Software Description:
- samba: SMB/CIFS file, print, and login server for Unix

Details:

Tom Tervoort discovered that the Netlogon protocol implemented by Samba
incorrectly handled the authentication scheme. A remote attacker could use
this issue to forge an authentication token and steal the credentials of
the domain admin.

This update fixes the issue by changing the "server schannel" setting to
default to "yes", instead of "auto", which will force a secure netlogon
channel. This may result in compatibility issues with older devices. A
future update may allow a finer-grained control over this setting.

Update instructions:

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

Ubuntu 18.04 LTS:
samba 2:4.7.6+dfsg~ubuntu-0ubuntu2.19

Ubuntu 16.04 LTS:
samba 2:4.3.11+dfsg-0ubuntu0.16.04.30

In general, a standard system update will make all the necessary changes.

References:
  https://usn.ubuntu.com/4510-1
CVE-2020-1472

Package Information:
  https://launchpad.net/ubuntu/+source/samba/2:4.7.6+dfsg~ubuntu-0ubuntu2.19
  https://launchpad.net/ubuntu/+source/samba/2:4.3.11+dfsg-0ubuntu0.16.04.30