Ralph Dolmans and Karst Koymans discovered that Unbound did not properly handle certain NSEC records. An attacker could use this to to prove the non-existence (NXDOMAIN answer) of an existing wildcard record, or trick Unbound into accepting a NODATA proof. Updated unbound packages now available for Ubuntu 18.04 LTS, 17.10, 16.04 LTS, and 14.04 LTS

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Ubuntu Security Notice USN-3673-1
June 07, 2018

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

- Ubuntu 18.04 LTS
- Ubuntu 17.10
- Ubuntu 16.04 LTS
- Ubuntu 14.04 LTS

Summary:

A security issue was fixed in Unbound.

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

Details:

Ralph Dolmans and Karst Koymans discovered that Unbound did not properly
handle certain NSEC records. An attacker could use this to to prove the
non-existence (NXDOMAIN answer) of an existing wildcard record, or trick
Unbound into accepting a NODATA proof.

Update instructions:

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

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

Ubuntu 17.10:
libunbound2 1.6.5-1ubuntu0.2
unbound 1.6.5-1ubuntu0.2

Ubuntu 16.04 LTS:
libunbound2 1.5.8-1ubuntu1.1
unbound 1.5.8-1ubuntu1.1

Ubuntu 14.04 LTS:
libunbound2 1.4.22-1ubuntu4.14.04.3
unbound 1.4.22-1ubuntu4.14.04.3

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

References:
https://usn.ubuntu.com/usn/usn-3673-1
CVE-2017-15105

Package Information:
https://launchpad.net/ubuntu/+source/unbound/1.6.7-1ubuntu2.1
https://launchpad.net/ubuntu/+source/unbound/1.6.5-1ubuntu0.2
https://launchpad.net/ubuntu/+source/unbound/1.5.8-1ubuntu1.1
https://launchpad.net/ubuntu/+source/unbound/1.4.22-1ubuntu4.14.04.3

  Unbound Security Update for Ubuntu