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Ubuntu Security Notice USN-6791-1
May 28, 2024

unbound vulnerability

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

• Ubuntu 24.04 LTS
• Ubuntu 23.10
• Ubuntu 22.04 LTS
• Ubuntu 20.04 LTS

Summary:

Unbound could be made to take part in a denial of service attack.

Software Description:

• unbound: validating, recursive, caching DNS resolver

Details:

It was discovered that Unbound could take part in a denial of service
amplification attack known as DNSBomb. This update introduces certain
resource limits to make the impact from Unbound significantly lower.

Update instructions:

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

Ubuntu 24.04 LTS
libunbound8 1.19.2-1ubuntu3.1
unbound 1.19.2-1ubuntu3.1

Ubuntu 23.10
libunbound8 1.17.1-2ubuntu0.2
unbound 1.17.1-2ubuntu0.2

Ubuntu 22.04 LTS
libunbound8 1.13.1-1ubuntu5.5
unbound 1.13.1-1ubuntu5.5

Ubuntu 20.04 LTS
libunbound8 1.9.4-2ubuntu1.6
unbound 1.9.4-2ubuntu1.6

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

References:
https://ubuntu.com/security/notices/USN-6791-1
CVE-2024-33655

Package Information:
https://launchpad.net/ubuntu/+source/unbound/1.19.2-1ubuntu3.1
https://launchpad.net/ubuntu/+source/unbound/1.17.1-2ubuntu0.2
https://launchpad.net/ubuntu/+source/unbound/1.13.1-1ubuntu5.5
https://launchpad.net/ubuntu/+source/unbound/1.9.4-2ubuntu1.6