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Ubuntu Security Notice USN-5126-2
October 28, 2021

bind9 vulnerability
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 16.04 ESM
- Ubuntu 14.04 ESM

Summary:

Bind could be made to consume resources if it received specially crafted
network traffic.

Software Description:
- bind9: Internet Domain Name Server

Details:

USN-5126-1 fixed a vulnerability in Bind. This update provides
the corresponding update for Ubuntu 14.04 ESM and Ubuntu 16.04 ESM.

Original advisory details:

 Kishore Kumar Kothapalli discovered that Bind incorrectly handled the lame
 cache when processing responses. A remote attacker could possibly use this
 issue to cause Bind to consume resources, resulting in a denial of service.

Update instructions:

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

Ubuntu 16.04 ESM:
  bind9                           1:9.10.3.dfsg.P4-8ubuntu1.19+esm1

Ubuntu 14.04 ESM:
  bind9                           1:9.9.5.dfsg-3ubuntu0.19+esm5

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

References:
  https://ubuntu.com/security/notices/USN-5126-2
  https://ubuntu.com/security/notices/USN-5126-1
  CVE-2021-25219