==========================================================================
Ubuntu Security Notice USN-6723-1
April 09, 2024

bind9 vulnerabilities
==========================================================================

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

- Ubuntu 18.04 LTS (Available with Ubuntu Pro)
- Ubuntu 16.04 LTS (Available with Ubuntu Pro)
- Ubuntu 14.04 LTS (Available with Ubuntu Pro)

Summary:

Bind could be made to crash if it received specially crafted
input.

Software Description:
- bind9: Internet Domain Name Server

Details:

Elias Heftrig, Haya Schulmann, Niklas Vogel, and Michael Waidner discovered
that Bind icorrectly handled validating DNSSEC messages. A remote attacker
could possibly use this issue to cause Bind to consume resources, leading
to a denial of service. (CVE-2023-50387)

It was discovered that Bind incorrectly handled preparing an NSEC3 closest
encloser proof. A remote attacker could possibly use this issue to cause
Bind to consume resources, leading to a denial of service. (CVE-2023-50868)

Update instructions:

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

Ubuntu 18.04 LTS (Available with Ubuntu Pro):
   bind9                           1:9.11.3+dfsg-1ubuntu1.19+esm3

Ubuntu 16.04 LTS (Available with Ubuntu Pro):
   bind9                           1:9.10.3.dfsg.P4-8ubuntu1.19+esm8

Ubuntu 14.04 LTS (Available with Ubuntu Pro):
   bind9                           1:9.9.5.dfsg-3ubuntu0.19+esm12

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

References:
   https://ubuntu.com/security/notices/USN-6723-1
   CVE-2023-50387, CVE-2023-50868