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Ubuntu Security Notice USN-4754-3
March 12, 2021

python2.7, python3.7, python3.8 vulnerabilities
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS

Summary:

Several security issues were fixed in Python 2.7 and Python 3.8.

Software Description:
- python2.7: An interactive high-level object-oriented language
- python3.7: An interactive high-level object-oriented language
- python3.8: An interactive high-level object-oriented language

Details:

USN-4754-1 fixed vulnerabilities in Python. This update provides
the corresponding updates for Ubuntu 18.04 ESM and Ubuntu 20.04 ESM.

In the case of Python 2.7 for 20.04 ESM, these additional fixes are included:

It was dicovered that Python allowed remote attackers to cause a denial of
service (resource consumption) via a ZIP bomb. (CVE-2019-9674)

It was discovered that Python had potentially misleading information about
whether sorting occurs. This fix updates the documentation about it.
(CVE-2019-17514)

It was discovered that Python incorrectly handled certain TAR archives.
An attacker could possibly use this issue to cause a denial of service.
(CVE-2019-20907)

It was discovered that Python allowed an HTTP server to conduct Regular
Expression Denial of Service (ReDoS) attacks against a client because of
urllib.request.AbstractBasicAuthHandler catastrophic backtracking.
(CVE-2020-8492)

It was discovered that Python allowed CRLF injection if the attacker controls
the HTTP request method, as demonstrated by inserting CR and LF control
characters in the first argument of HTTPConnection.request. (CVE-2020-26116)

Original advisory details:

 It was discovered that Python incorrectly handled certain inputs.
 An attacker could possibly use this issue to execute arbitrary code
 or cause a denial of service. (CVE-2020-27619, CVE-2021-3177)

Update instructions:

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

Ubuntu 20.04 LTS:
  python2.7                       2.7.18-1~20.04.1
  python2.7-minimal               2.7.18-1~20.04.1

Ubuntu 18.04 LTS:
  python3.7                       3.7.5-2~18.04.4
  python3.7-minimal               3.7.5-2~18.04.4
  python3.8                       3.8.0-3~18.04.1
  python3.8-minimal               3.8.0-3~18.04.1

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

References:
  https://ubuntu.com/security/notices/USN-4754-3
  https://ubuntu.com/security/notices/USN-4754-1
  CVE-2019-17514, CVE-2019-20907, CVE-2019-9674, CVE-2020-26116,
  CVE-2020-27619, CVE-2020-8492, CVE-2021-3177

Package Information:
  https://launchpad.net/ubuntu/+source/python2.7/2.7.18-1~20.04.1
  https://launchpad.net/ubuntu/+source/python3.7/3.7.5-2~18.04.4
  https://launchpad.net/ubuntu/+source/python3.8/3.8.0-3~18.04.1