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Ubuntu Security Notice USN-4931-1
May 03, 2021

samba vulnerabilities
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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:
  https://ubuntu.com/security/notices/USN-4931-1
  CVE-2020-14318, CVE-2020-14323, CVE-2020-14383, CVE-2021-20254