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SAML XML Signature wrapping in PySAML2

Moderate severity GitHub Reviewed Published Jan 20, 2021 in IdentityPython/pysaml2 • Updated Oct 14, 2024

Package

pip pysaml2 (pip)

Affected versions

< 6.5.0

Patched versions

6.5.0

Description

Impact

All users of pysaml2 that use the default CryptoBackendXmlSec1 backend and need to verify signed SAML documents are impacted. pysaml2 <= 6.4.1 does not validate the SAML document against an XML schema. This allows invalid XML documents to trick the verification process, by presenting elements with a valid signature inside elements whose content has been malformed. The verification is offloaded to xmlsec1 and xmlsec1 will not validate every signature in the given document, but only the first it finds in the given scope.

Patches

Users should upgrade to pysaml2 v6.5.0.

Workarounds

No workaround provided at this point.

References

No references provided at this point.

Credits

  • Victor Schönfelder Garcia (isits AG International School of IT Security)
  • Juraj Somorovsky (Paderborn University)
  • Vladislav Mladenov (Ruhr University Bochum)

For more information

If you have any questions or comments about this advisory:

References

@c00kiemon5ter c00kiemon5ter published to IdentityPython/pysaml2 Jan 20, 2021
Reviewed Jan 21, 2021
Published to the GitHub Advisory Database Jan 21, 2021
Published by the National Vulnerability Database Jan 21, 2021
Last updated Oct 14, 2024

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

EPSS score

0.107%
(44th percentile)

Weaknesses

CVE ID

CVE-2021-21238

GHSA ID

GHSA-f4g9-h89h-jgv9

Source code

Credits

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