=========================================================================Ubuntu Security Notice USN-5201-1
December 17, 2021

python3.8, python3.9 vulnerabilities
=========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 21.04
- Ubuntu 20.04 LTS

Summary:

Python could be made to crash if it receives specially crafted input 
from a malicious server.

Software Description:
- python3.9: Interactive high-level object-oriented language (version 3.9)
- python3.8: An interactive high-level object-oriented language

Details:

It was discovered that the Python urllib http client could enter into an 
infinite loop when incorrectly handling certain server responses (100 
Continue response). Specially crafted traffic from a malicious HTTP 
server could cause a denial of service (Dos) condition for a client.
(CVE-2021-3737)

Update instructions:

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

Ubuntu 21.04:
   libpython3.9-stdlib             3.9.5-3ubuntu0~21.04.1
   python3.9                          3.9.5-3ubuntu0~21.04.1
   python3.9-minimal             3.9.5-3ubuntu0~21.04.1

Ubuntu 20.04 LTS:
   libpython3.8-stdlib             3.8.10-0ubuntu1~20.04.2
   libpython3.9-stdlib             3.9.5-3ubuntu0~20.04.1
   python3.8                          3.8.10-0ubuntu1~20.04.2
   python3.8-minimal             3.8.10-0ubuntu1~20.04.2
   python3.9                          3.9.5-3ubuntu0~20.04.1
   python3.9-minimal             3.9.5-3ubuntu0~20.04.1

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

References:
   https://ubuntu.com/security/notices/USN-5201-1
   CVE-2021-3737

Package Information:
   https://launchpad.net/ubuntu/+source/python3.9/3.9.5-3ubuntu0~21.04.1
   https://launchpad.net/ubuntu/+source/python3.8/3.8.10-0ubuntu1~20.04.2
   https://launchpad.net/ubuntu/+source/python3.9/3.9.5-3ubuntu0~20.04.1