A PySAML2 security update has been released for Ubuntu Linux 18.04 LTS, 20.04 LTS, and 21.04.

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Ubuntu Security Notice USN-5066-1
September 08, 2021

python-pysaml2 vulnerability
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 21.04
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS

Summary:

PySAML2 could be made to accept invalid SAML documents.

Software Description:
- python-pysaml2: Pure python implementation of SAML2

Details:

Brian Wolff discovered that PySAML2 incorrectly validated cryptographic
signatures. A remote attacker could possibly use this issue to alter SAML
documents.

Update instructions:

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

Ubuntu 21.04:
python3-pysaml2 6.1.0-0ubuntu1.21.04.1

Ubuntu 20.04 LTS:
python3-pysaml2 4.9.0-0ubuntu3.1

Ubuntu 18.04 LTS:
python-pysaml2 4.0.2-0ubuntu3.2
python3-pysaml2 4.0.2-0ubuntu3.2

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

References:
  https://ubuntu.com/security/notices/USN-5066-1
CVE-2021-21239

Package Information:
  https://launchpad.net/ubuntu/+source/python-pysaml2/6.1.0-0ubuntu1.21.04.1
  https://launchpad.net/ubuntu/+source/python-pysaml2/4.9.0-0ubuntu3.1
  https://launchpad.net/ubuntu/+source/python-pysaml2/4.0.2-0ubuntu3.2