A python-py security update has been released for Ubuntu Linux 18.04 LTS and 20.04 LTS.

USN-5138-1: python-py vulnerability

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Ubuntu Security Notice USN-5138-1
November 10, 2021

python-py vulnerability
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS

Summary:

python-py could be made to crash if provided with specially crafted input.

Software Description:
- python-py: Advanced Python development support library

Details:

The py.path.svnwc component of py (aka python-py) through v1.9.0
contains a regular expression with an ambiguous subpattern that is
susceptible to catastrophic backtracing. This could be used by attackers
to cause a compute-time denial of service attack by supplying malicious
input to the blame functionality.

Update instructions:

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

Ubuntu 20.04 LTS:
pypy-py 1.8.1-1ubuntu0.1
python-py 1.8.1-1ubuntu0.1
python3-py 1.8.1-1ubuntu0.1

Ubuntu 18.04 LTS:
pypy-py 1.5.2-1ubuntu0.1
python-py 1.5.2-1ubuntu0.1
python3-py 1.5.2-1ubuntu0.1

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

References:
  https://ubuntu.com/security/notices/USN-5138-1
CVE-2020-29651

Package Information:
  https://launchpad.net/ubuntu/+source/python-py/1.8.1-1ubuntu0.1
  https://launchpad.net/ubuntu/+source/python-py/1.5.2-1ubuntu0.1