[USN-6425-2] Samba regression

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==========================================================================
Ubuntu Security Notice USN-6425-2
October 11, 2023

samba regression
==========================================================================

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

- Ubuntu 20.04 LTS

Summary:

USN-6425-1 introduced a regression in Samba.

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

Details:

USN-6425-1 fixed vulnerabilities in Samba. Due to a build issue on Ubuntu
20.04 LTS, the update introduced regressions in macro handling and
possibly other functionality.

This update fixes the problem. We apologize for the inconvenience.

Original advisory details:

Sri Nagasubramanian discovered that the Samba acl_xattr VFS module
incorrectly handled read-only files. When Samba is configured to ignore
system ACLs, a remote attacker could possibly use this issue to truncate
read-only files. (CVE-2023-4091)
Andrew Bartlett discovered that Samba incorrectly handled the DirSync
control. A remote attacker with an RODC DC account could possibly use this
issue to obtain all domain secrets. (CVE-2023-4154)
Andrew Bartlett discovered that Samba incorrectly handled the rpcecho
development server. A remote attacker could possibly use this issue to
cause Samba to stop responding, resulting in a denial of service.
(CVE-2023-42669)
Kirin van der Veer discovered that Samba incorrectly handled certain RPC
service listeners. A remote attacker could possibly use this issue to cause
Samba to start multiple incompatible RPC listeners, resulting in a denial
of service. This issue only affected Ubuntu 22.04 LTS, and Ubuntu 23.04.
(CVE-2023-42670)

Update instructions:

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

Ubuntu 20.04 LTS:
samba 2:4.15.13+dfsg-0ubuntu0.20.04.7

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

References:
https://ubuntu.com/security/notices/USN-6425-2
https://ubuntu.com/security/notices/USN-6425-1
https://launchpad.net/bugs/2039031

Package Information:
https://launchpad.net/ubuntu/+source/samba/2:4.15.13+dfsg-0ubuntu0.20.04.7