A python-pysaml2 security update has been released for Debian GNU/Linux 9 LTS to address several issues.

DLA 2577-1: python-pysaml2 security update

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Debian LTS Advisory DLA-2577-1 debian-lts@lists.debian.org
  https://www.debian.org/lts/security/ Abhijith PA
February 26, 2021   https://wiki.debian.org/LTS
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Package : python-pysaml2
Version : 3.0.0-5+deb9u2
CVE ID : CVE-2017-1000433 CVE-2021-21239
Debian Bug : 886423 CVE-2021-21239

Several issues have been found in python-pysaml2, a pure python
implementation of SAML Version 2 Standard.

CVE-2017-1000433

pysaml2 accept any password when run with python optimizations
enabled. This allows attackers to log in as any user without
knowing their password.

CVE-2021-21239

pysaml2 has an improper verification of cryptographic signature
vulnerability. Users of pysaml2 that use the default
CryptoBackendXmlSec1 backend and need to verify signed SAML
documents are impacted. PySAML2 does not ensure that a signed
SAML document is correctly signed. The default
CryptoBackendXmlSec1 backend is using the xmlsec1 binary to
verify the signature of signed SAML documents, but by default
xmlsec1 accepts any type of key found within the given document.
xmlsec1 needs to be configured explicitly to only use only _x509
certificates_ for the verification process of the SAML document signature.

For Debian 9 stretch, these problems have been fixed in version
3.0.0-5+deb9u2.

We recommend that you upgrade your python-pysaml2 packages.

For the detailed security status of python-pysaml2 please refer to
its security tracker page at:
  https://security-tracker.debian.org/tracker/python-pysaml2

Further information about Debian LTS security advisories, how to apply
these updates to your system and frequently asked questions can be
found at:   https://wiki.debian.org/LTS