{"schema_version":"1.9.0","id":"GHSA-5p3x-r448-pc62","published":"2021-01-21T14:12:18Z","modified":"2026-09-10T03:49:13.846262945Z","aliases":["CVE-2021-21239","PYSEC-2021-49"],"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","affected":[{"package":{"name":"pysaml2","ecosystem":"PyPI","purl":"pkg:pypi/pysaml2"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.5.0"}]}],"versions":["0.4.3","1.0.1","1.0.2","1.0.3","1.1.0","2.0.0","2.1.0","2.2.0","2.3.0","2.4.0","3.0.0","3.0.2","4.0.0","4.0.1","4.0.2","4.0.3","4.0.4","4.0.5","4.0.5rc1","4.1.0","4.2.0","4.3.0","4.4.0","4.5.0","4.6.0","4.6.1","4.6.2","4.6.3","4.6.4","4.6.5","4.7.0","4.8.0","4.9.0","5.0.0","5.1.0","5.2.0","5.3.0","5.4.0","6.0.0","6.1.0","6.2.0","6.3.0","6.3.1","6.4.0","6.4.1"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2021/01/GHSA-5p3x-r448-pc62/GHSA-5p3x-r448-pc62.json"}}],"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"],"github_reviewed":true,"github_reviewed_at":"2021-01-21T14:11:58Z","nvd_published_at":"2021-01-21T15:15:00Z","severity":"MODERATE"},"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"}]}