USN-3407-1: PyJWT vulnerability

30 August 2017

pyjwt vulnerability

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

  • Ubuntu 17.04
  • Ubuntu 16.04 LTS


PyJWT could be made to crash if it received specially crafted input.

Software Description

  • pyjwt - Python implementation of JSON Web Token


It was discovered that a vulnerability in PyJWT doesn’t check invalid_strings properly for some public keys. A remote attacker could take advantage of a key confusion to craft JWTs from scratch.

Update instructions

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

Ubuntu 17.04
python-jwt - 1.4.2-1ubuntu0.1
python3-jwt - 1.4.2-1ubuntu0.1
Ubuntu 16.04 LTS
python-jwt - 1.3.0-1ubuntu0.1
python3-jwt - 1.3.0-1ubuntu0.1

To update your system, please follow these instructions:

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