USN-3138-1: python-cryptography vulnerability

28 November 2016

python-cryptography vulnerability

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

  • Ubuntu 16.10
  • Ubuntu 16.04 LTS


python-cryptography could generate incorrect keys.

Software Description

  • python-cryptography - Cryptography Python library


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

To update your system, please follow these instructions:

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