=========================================================================Ubuntu Security Notice USN-3138-1
November 28, 2016

python-cryptography vulnerability
=========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 16.10
- Ubuntu 16.04 LTS

Summary:

python-cryptography could generate incorrect keys.

Software Description:
- python-cryptography: Cryptography Python library

Details:

Markus Döring discovered that python-cryptography incorrectly handled
certain HKDF lengths. This could result in python-cryptography returning an
empty string instead of the expected derived key.

Update instructions:

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

Ubuntu 16.10:
  python-cryptography             1.5-2ubuntu0.1
  python3-cryptography            1.5-2ubuntu0.1

Ubuntu 16.04 LTS:
  python-cryptography             1.2.3-1ubuntu0.1
  python3-cryptography            1.2.3-1ubuntu0.1

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

References:
  https://ubuntu.com/security/notices/USN-3138-1
  CVE-2016-9243

Package Information:
  https://launchpad.net/ubuntu/+source/python-cryptography/1.5-2ubuntu0.1
  https://launchpad.net/ubuntu/+source/python-cryptography/1.2.3-1ubuntu0.1