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Ubuntu Security Notice USN-4374-1
May 27, 2020

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

- Ubuntu 20.04 LTS
- Ubuntu 19.10
- Ubuntu 18.04 LTS

Summary:

Several security issues were fixed in Unbound.

Software Description:
- unbound: validating, recursive, caching DNS resolver

Details:

Lior Shafir, Yehuda Afek, and Anat Bremler-Barr discovered that Unbound
incorrectly handled certain queries. A remote attacker could use this issue
to perform an amplification attack directed at a target. (CVE-2020-12662)

It was discovered that Unbound incorrectly handled certain malformed
answers. A remote attacker could possibly use this issue to cause Unbound
to crash, resulting in a denial of service. (CVE-2020-12663)

Update instructions:

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

Ubuntu 20.04 LTS:
  libunbound8                     1.9.4-2ubuntu1.1
  unbound                         1.9.4-2ubuntu1.1

Ubuntu 19.10:
  libunbound8                     1.9.0-2ubuntu1.1
  unbound                         1.9.0-2ubuntu1.1

Ubuntu 18.04 LTS:
  libunbound2                     1.6.7-1ubuntu2.3
  unbound                         1.6.7-1ubuntu2.3

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

References:
  https://usn.ubuntu.com/4374-1
  CVE-2020-12662, CVE-2020-12663

Package Information:
  https://launchpad.net/ubuntu/+source/unbound/1.9.4-2ubuntu1.1
  https://launchpad.net/ubuntu/+source/unbound/1.9.0-2ubuntu1.1
  https://launchpad.net/ubuntu/+source/unbound/1.6.7-1ubuntu2.3