# CVE-2021-21238: SAML XML Signature wrapping in PySAML2

Source: https://junglewise.ai/threats/cve-2021-21238-saml-xml-signature-wrapping-in-pysaml2  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2021-01-21  
License: CC BY 4.0 with a link back

CVE-2021-21238 · Severity: low · CVSS 3.1 · Published 2021-01-21

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.

Technologies: [pysaml2 (PyPI)](https://junglewise.ai/threats/technologies/pypi-pysaml2). Vendors: [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2021-21238 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2021-21238 being exploited in the wild.

**How severe is CVE-2021-21238?** Low severity, with a CVSS score of 3.1, published 21 January 2021.

**Which products and versions are affected?** pysaml2 (PyPI) ECOSYSTEM:introduced=0,fixed=6.5.0, GIT:introduced=0,fixed=1d8fd268f5bf887480a403a7a5ef8f048157cc14|ECOSYSTEM:introduced=0,fixed=6.5.0.

**Is there a fix for CVE-2021-21238?** Yes. pysaml2 (PyPI): upgrade to 6.5.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**Am I affected by CVE-2021-21238?** Check whether you run pysaml2 (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- pysaml2 (PyPI): upgrade to 6.5.0 or later

  ```sh
  pip install "pysaml2>=6.5.0"
  ```


## Affected products

- pysaml2 (PyPI) ECOSYSTEM:introduced=0,fixed=6.5.0, GIT:introduced=0,fixed=1d8fd268f5bf887480a403a7a5ef8f048157cc14|ECOSYSTEM:introduced=0,fixed=6.5.0

## Identifiers

- CVE-2021-21238
- GHSA-f4g9-h89h-jgv9
- PYSEC-2021-48

## Related threats

- [Improper Verification of Cryptographic Signature in PySAML2](https://junglewise.ai/threats/cve-2021-21239-improper-verification-of-cryptographic-signature-in-pysaml2)
- [Improper Verification of Cryptographic Signature in PySAML2](https://junglewise.ai/threats/cve-2020-5390-improper-verification-of-cryptographic-signature-in-pysaml2)
- [pysaml2 Improper Authentication vulnerability](https://junglewise.ai/threats/cve-2017-1000433-pysaml2-improper-authentication-vulnerability)
- [Pysaml2 improperly initializes encryption vector](https://junglewise.ai/threats/cve-2017-1000246-pysaml2-improperly-initializes-encryption-vector)
- [Pysaml2 does not sanitize XML responses](https://junglewise.ai/threats/cve-2016-10149-pysaml2-does-not-sanitize-xml-responses)