medium6.5

CVE-2021-21239

Improper Verification of Cryptographic Signature in PySAML2

Impact

### 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 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. ### Patches Users should upgrade to pysaml2 `v6.5.0`. ### Workarounds No workaround provided at this point. ### References This issue has been reported in the past at the xmlsec1 mailing list: https://www.aleksey.com/pipermail/xmlsec/2013/009717.html ### Credits - Brian Wolff ### For more information If you have any questions or comments about this advisory: * Open an issue in [pysaml2](https://github.com/IdentityPython/pysaml2) * Email us at [the incident-response address](mailto:incident-response@idpy.org)

Affected packages

Ecosystem	Package	Affected	Fixed in
pip	`pysaml2`	< 6.5.0	6.5.0

Affected products

Vendor	Product	Affected versions
Pysaml2 Project	Pysaml2	before 6.5.0
Debian	Debian Linux	Version 9.0

Weakness classification

CWE-347