CVE-2021-21239: Pysaml2 Improper Verification Of Cryptographic Signature Vulnerability
MODERATECVE-2021-21239 is a MODERATE (CVSS 6.5) 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 6.5.0.
CVE-2021-21239 at a Glance
Security Impact
CVSS: 6.5
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:R/S:U/C:N/I:H/A:N).
How to Fix CVE-2021-21239
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.
pip install pysaml2>=6.5.0Run the following command in your project directory to verify that all resolved dependencies use the patched release:
pip show pysaml2How to Check if You Are Affected
To determine whether your Python environment is affected by CVE-2021-21239, inspect your installed packages using pip:
pip show pysaml2Analyze 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 6.5.0), 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
CVE-2021-21239 Affected Pysaml2 Versions
1 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
pysaml2
|
PyPI |
< 6.5.0
|
6.5.0
|
References
Frequently Asked Questions
What is CVE-2021-21239?
Which Pysaml2 versions are affected?
What version fixes CVE-2021-21239?
Is pysaml2 affected?
What is the CVSS score of CVE-2021-21239?
What CWE is associated with CVE-2021-21239?
How can I check PyPI dependencies for CVE-2021-21239?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-5p3x-r448-pc62",
"modified" : "2024-10-14T15:41:51Z",
"published" : "2021-01-21T14:12:18Z",
"aliases" : [ "CVE-2021-21239" ],
"summary" : "Improper Verification of Cryptographic Signature in PySAML2",
"details" : "### Impact\n\nAll 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.\n\n### Patches\n\nUsers should upgrade to pysaml2 `v6.5.0`.\n\n### Workarounds\n\nNo workaround provided at this point.\n\n### References\n\nThis issue has been reported in the past at the xmlsec1 mailing list:\nhttps://www.aleksey.com/pipermail/xmlsec/2013/009717.html\n\n### Credits\n\n- Brian Wolff\n\n### For more information\n\nIf you have any questions or comments about this advisory:\n* Open an issue in [pysaml2](https://github.com/IdentityPython/pysaml2)\n* Email us at [the incident-response address](mailto:incident-response@idpy.org)\n",
"severity" : [ {
"type" : "CVSS_V3",
"score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N"
}, {
"type" : "CVSS_V4",
"score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "PyPI",
"name" : "pysaml2"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "0"
}, {
"fixed" : "6.5.0"
} ]
} ]
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/IdentityPython/pysaml2/security/advisories/GHSA-5p3x-r448-pc62"
}, {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-21239"
}, {
"type" : "WEB",
"url" : "https://github.com/IdentityPython/pysaml2/commit/46578df0695269a16f1c94171f1429873f90ed99"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/IdentityPython/pysaml2"
}, {
"type" : "WEB",
"url" : "https://github.com/IdentityPython/pysaml2/releases/tag/v6.5.0"
}, {
"type" : "WEB",
"url" : "https://github.com/pypa/advisory-database/tree/main/vulns/pysaml2/PYSEC-2021-49.yaml"
}, {
"type" : "WEB",
"url" : "https://lists.debian.org/debian-lts-announce/2021/02/msg00038.html"
}, {
"type" : "WEB",
"url" : "https://pypi.org/project/pysaml2"
}, {
"type" : "WEB",
"url" : "https://www.aleksey.com/pipermail/xmlsec/2013/009717.html"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-347" ],
"severity" : "MODERATE",
"github_reviewed" : true,
"github_reviewed_at" : "2021-01-21T14:11:58Z",
"nvd_published_at" : "2021-01-21T15:15:00Z"
}
}