CVE-2020-5390: Pysaml2 Improper Verification Of Cryptographic Signature Vulnerability

HIGH
Advisory Identifier: GHSA-qf7v-8hj3-4xw7
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CVSS 7.5
CWE-347
Published
Advisory Summary

CVE-2020-5390 is a HIGH (CVSS 7.5) improper verification of cryptographic signature vulnerability (CWE-347: Improper Verification of Cryptographic Signature) affecting Pysaml2 libraries in the PyPI ecosystem. The issue involves improper verification of cryptographic signature in pysaml2. Remediation is available by upgrading affected packages to version 5.0.0.

CVE-2020-5390 at a Glance

CVE Identifier CVE-2020-5390
GHSA Identifier GHSA-qf7v-8hj3-4xw7
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-347: Improper Verification of Cryptographic Signature
Affected Product Pysaml2
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 7.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity High (I:H)
Availability None (A:N)

How to Fix CVE-2020-5390

To remediate this vulnerability, upgrade all affected Pysaml2 dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

pysaml2 fixed: 5.0.0 
pip install pysaml2>=5.0.0
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show pysaml2

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2020-5390, inspect your installed packages using pip:

pip show pysaml2

Analyze the terminal output to locate any version of Pysaml2 in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 5.0.0), your application is affected.

Note: The pip show pysaml2 command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-347: Improper Verification of Cryptographic Signature, where the product does not verify, or incorrectly verifies, the cryptographic signature for data. In Pysaml2, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

PySAML2 before 5.0.0 does not check that the signature in a SAML document is enveloped and thus signature wrapping is effective, i.e., it is affected by XML Signature Wrapping (XSW). The signature information and the node/object that is signed can be in different places and thus the signature verification will succeed, but the wrong data will be used. This specifically affects the verification of assertions that have been signed.

CVE-2020-5390 Affected Pysaml2 Versions

1 component(s)
Fixed Versions:
5.0.0
Product / Package Ecosystem Affected Versions Fixed Version
pysaml2
pypi/pysaml2
PyPI
< 5.0.0
5.0.0

References

NVD — CVE-2020-5390 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-5390
Security Fix Commit FIX COMMIT
https://github.com/IdentityPython/pysaml2/commit/5e9d5acbcd8ae45c4e736ac521fd2df5b1c62e25
Security Fix Commit FIX COMMIT
https://github.com/IdentityPython/pysaml2/commit/f27c7e7a7010f83380566a219fd6a290a00f2b6e
Pysaml2 Source Repository REPOSITORY
https://github.com/IdentityPython/pysaml2
Pysaml2 Source Repository REPOSITORY
https://github.com/IdentityPython/pysaml2/blob/master/CHANGELOG.md#500-2020-01-13
Pysaml2 Source Repository REPOSITORY
https://github.com/IdentityPython/pysaml2/releases
Pysaml2 Release RELEASE
https://github.com/IdentityPython/pysaml2/releases/tag/v5.0.0
GitHub Advisory / Wiki ADVISORY
https://github.com/advisories/GHSA-qf7v-8hj3-4xw7
Pysaml2 Source Repository REPOSITORY
https://github.com/pypa/advisory-database/tree/main/vulns/pysaml2/PYSEC-2020-94.yaml
lists.debian.org/debian-lts-announce... WEB
https://lists.debian.org/debian-lts-announce/2020/02/msg00025.html
pypi.org/project/pysaml2/5.0... WEB
https://pypi.org/project/pysaml2/5.0.0
usn.ubuntu.com/4245-1 WEB
https://usn.ubuntu.com/4245-1
Pysaml2 Security Information SECURITY
https://www.debian.org/security/2020/dsa-4630

Frequently Asked Questions

What is CVE-2020-5390?
CVE-2020-5390 is a security vulnerability in Pysaml2 involving Improper Verification of Cryptographic Signature in PySAML2 under CWE-347: Improper Verification of Cryptographic Signature.
Which Pysaml2 versions are affected?
Affected versions include releases prior to 5.0.0 across affected packages: pysaml2.
What version fixes CVE-2020-5390?
Upgrading to 5.0.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is pysaml2 affected?
Yes, pysaml2 is affected in releases prior to 5.0.0. Upgrade your dependency to 5.0.0 or later.
What is the CVSS score of CVE-2020-5390?
CVE-2020-5390 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N.
What CWE is associated with CVE-2020-5390?
CVE-2020-5390 is classified under CWE-347: Improper Verification of Cryptographic Signature (The product does not verify, or incorrectly verifies, the cryptographic signature for data.).
How can I check PyPI dependencies for CVE-2020-5390?
Run the dependency tree command: 'pip show pysaml2'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-qf7v-8hj3-4xw7",
  "modified" : "2024-10-23T15:55:36Z",
  "published" : "2020-05-06T19:41:29Z",
  "aliases" : [ "CVE-2020-5390" ],
  "summary" : "Improper Verification of Cryptographic Signature in PySAML2",
  "details" : "PySAML2 before 5.0.0 does not check that the signature in a SAML document is enveloped and thus signature wrapping is effective, i.e., it is affected by XML Signature Wrapping (XSW). The signature information and the node/object that is signed can be in different places and thus the signature verification will succeed, but the wrong data will be used. This specifically affects the verification of assertions that have been signed.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
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      "ecosystem" : "PyPI",
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    },
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      "type" : "ECOSYSTEM",
      "events" : [ {
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      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-5390"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/IdentityPython/pysaml2/commit/5e9d5acbcd8ae45c4e736ac521fd2df5b1c62e25"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/IdentityPython/pysaml2/commit/f27c7e7a7010f83380566a219fd6a290a00f2b6e"
  }, {
    "type" : "PACKAGE",
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  }, {
    "type" : "WEB",
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  }, {
    "type" : "WEB",
    "url" : "https://github.com/IdentityPython/pysaml2/releases"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/IdentityPython/pysaml2/releases/tag/v5.0.0"
  }, {
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  }, {
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  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2020/02/msg00025.html"
  }, {
    "type" : "WEB",
    "url" : "https://pypi.org/project/pysaml2/5.0.0"
  }, {
    "type" : "WEB",
    "url" : "https://usn.ubuntu.com/4245-1"
  }, {
    "type" : "WEB",
    "url" : "https://www.debian.org/security/2020/dsa-4630"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-347" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2020-05-06T19:39:39Z",
    "nvd_published_at" : "2020-01-13T19:15:00Z"
  }
}