The Pallets team is pleased to release Flask 1.0. [Read the announcement on our blog.](https://www.palletsprojects.com/blog/flask-1-0-released/

There are over a year's worth of changes in this release. Many features have been improved or changed. Read the changelog to understand how your project's code will be affected.

JSON Security Fix

Flask previously decoded incoming JSON bytes using the content type of the request. Although JSON should only be encoded as UTF-8, Flask was more lenient. However, Python includes non-text related encodings that could result in unexpected memory use by a request.

Flask will now detect the encoding of incoming JSON data as one of the supported UTF encodings, and will not allow arbitrary encodings from the request.

Install or Upgrade

Install from PyPI with pip:

pip install -U Flask