A Flask security update has been released for Ubuntu Linux 18.04 LTS, 16.04 LTS, and 14.04 ESM.

USN-4378-1: Flask vulnerability

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Ubuntu Security Notice USN-4378-1
June 01, 2020

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

- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS
- Ubuntu 14.04 ESM

Summary:

Flask could be made to consume a large amount of memory if it
received a specially crafted input.

Software Description:
- flask: Micro web framework based on Werkzeug and Jinja2

Details:

It was discovered that Flask incorrectly handled certain inputs.
An attacker could possibly use this issue to cause a denial of service.

Update instructions:

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

Ubuntu 18.04 LTS:
python-flask 0.12.2-3ubuntu0.1
python3-flask 0.12.2-3ubuntu0.1

Ubuntu 16.04 LTS:
python-flask 0.10.1-2ubuntu0.1
python3-flask 0.10.1-2ubuntu0.1

Ubuntu 14.04 ESM:
python-flask 0.10.1-2ubuntu0.1~esm1
python3-flask 0.10.1-2ubuntu0.1~esm1

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

References:
  https://usn.ubuntu.com/4378-1
CVE-2018-1000656

Package Information:
  https://launchpad.net/ubuntu/+source/flask/0.12.2-3ubuntu0.1
  https://launchpad.net/ubuntu/+source/flask/0.10.1-2ubuntu0.1