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CVE-2021-21239

6.5 · MEDIUM

PySAML2 is a pure python implementation of SAML Version 2 Standard.

Published Jan 21, 2021CWE-347EPSS 1.29%

Overview

CVE-2021-21239 is a medium-severity vulnerability. It was published on January 21, 2021 and has a CVSS 3.1 base score of 6.5 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 6.5, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

PySAML2 is a pure python implementation of SAML Version 2 Standard. PySAML2 before 6.5.0 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. This is fixed in PySAML2 6.5.0.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/IdentityPython/pysaml2/commit/46578df0695269a16f1c94171f1429873f90ed99GitHubgithub.com/IdentityPython/pysaml2/releases/tag/v6.5.0GitHubgithub.com/IdentityPython/pysaml2/security/advisories/GHSA-5p3x-r448-pc62Reflists.debian.org/debian-lts-announce/2021/02/msg00038.htmlRefpypi.org/project/pysaml2Refwww.aleksey.com/pipermail/xmlsec/2013/009717.htmlGitHubgithub.com/IdentityPython/pysaml2/commit/46578df0695269a16f1c94171f1429873f90ed99GitHubgithub.com/IdentityPython/pysaml2/releases/tag/v6.5.0GitHubgithub.com/IdentityPython/pysaml2/security/advisories/GHSA-5p3x-r448-pc62Reflists.debian.org/debian-lts-announce/2021/02/msg00038.html

How CyberStrike helps

Frequently asked questions

What is CVE-2021-21239?

CVE-2021-21239 is a medium-severity vulnerability. It was published on January 21, 2021 and has a CVSS 3.1 base score of 6.5 (MEDIUM).

How severe is CVE-2021-21239?

This vulnerability has a CVSS 3.1 base score of 6.5, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2021-21239?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2021-21239?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-21239 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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