[USN-4931-1] Samba vulnerabilities

========================================================================== Ubuntu Security Notice USN-4931-1 May 03, 2021
samba vulnerabilities ==========================================================================
A security issue affects these releases of Ubuntu and its derivatives:
– Ubuntu 14.04 ESM
Summary:
Several security issues were fixed in Samba.
Software Description: – samba: SMB/CIFS file, print, and login server for Unix
Details:
Steven French discovered that Samba incorrectly handled ChangeNotify permissions. A remote attacker could possibly use this issue to obtain file name information. (CVE-2020-14318)
Bas Alberts discovered that Samba incorrectly handled certain winbind requests. A remote attacker could possibly use this issue to cause winbind to crash, resulting in a denial of service. (CVE-2020-14323)
Francis Brosnan Blázquez discovered that Samba incorrectly handled certain invalid DNS records. A remote attacker could possibly use this issue to cause the DNS server to crash, resulting in a denial of service. (CVE-2020-14383)
Peter Eriksson discovered that Samba incorrectly handled certain negative idmap cache entries. This issue could result in certain users gaining unauthorized access to files, contrary to expected behaviour. (CVE-2021-20254)
Update instructions:
The problem can be corrected by updating your system to the following package versions:
Ubuntu 14.04 ESM:   samba                           2:4.3.11+dfsg-0ubuntu0.14.04.20+esm11
In general, a standard system update will make all the necessary changes.
References:   ubuntu.com/security/notices/USN-4931-1   CVE-2020-14318, CVE-2020-14323, CVE-2020-14383, CVE-2021-20254