CVE-2021-21238

SAML XML Signature wrapping

MEDIUM
6.5
CVSS Score
Published: January 21, 2021 at 02:15 PM UTC
Updated: June 17, 2026 at 03:35 AM UTC
2 products affected across 2 vendorsPYSAML2Project PYSAML2

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Severity
MEDIUM6.5
Exploit prediction
EPSS 1%

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. 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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 6.5.0
Affected range stops below 6.5.0, so it looks safe — our inference, not a vendor statement
v < 6.5.0
Affected range stops below 6.5.0, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

CVSS

6.5MEDIUMGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
NONE
Integrity
HIGH
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-347

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