SAML XML Signature wrapping in PySAML2

中 6.5CVE-2021-21238 · GHSA-f4g9-h89h-jgv9 · PYSEC-2021-48 · 21/01/2021 公開 · 17/06/2026 更新

要点

CVE-2021-21238 は pysaml2, pysaml2 (pysaml2 project) に影響する深刻度「中」 (CVSS 6.5) の脆弱性です。
今後30日間に悪用される確率（EPSS）：1.1%（全脆弱性の 65.7% より高い）。
対処：6.5.0 以降に更新してください。

パッケージ	影響を受けるバージョン	修正済みバージョン
pysaml2 PyPI	`< 6.5.0`	`6.5.0`
pysaml2 pysaml2_project	`< 6.5.0`	`6.5.0`

概要

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:

Open an issue in pysaml2
Email us at the incident-response address

NVD の説明

PySAML2 is a pure python implementation of SAML Version 2 Standard. PySAML2 before 6.5.0 has an improper verification of cryptographic signature vulnerability. All users of pysaml2 that need to validate signed SAML documents are impacted. The vulnerability is a variant of XML Signature wrapping because it did not validate the SAML document against an XML schema. This allowed invalid XML documents to be processed and such a document can trick pysaml2 with a wrapped signature. This is fixed in PySAML2 6.5.0.