{"id":"CVE-2020-27847","aliases":["EUVD-2021-2428","GHSA-2x32-jm95-2cpx"],"status":"published","title":"Authentication Bypass in dex","description":"A vulnerability exists in the SAML connector of the github.com/dexidp/dex library used to process SAML Signature Validation. This flaw allows an attacker to bypass SAML authentication. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability. This flaw affects dex versions before 2.27.0.","severity":{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"primary","from":"nvd"},"epss":{"day":"2026-11-11","score":0.01718,"percentile":0.77749,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-228","CWE-290","CWE-347"],"published":"2020-12-28T20:15:12.493Z","modified":"2026-10-20T10:53:01Z","fixes":[{"ecosystem":"Go","package":"github.com/dexidp/dex","fixed_in":["2.27.0"],"sources":["ghsa"]}],"affected":[{"source":"ghsa","ecosystem":"Go","package":"github.com/dexidp/dex","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.27.0"}]}]},{"source":"osv","ecosystem":"Go","package":"github.com/dexidp/dex","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2.27.0"}]}],"bundled":2},{"source":"osv","ecosystem":"Go","package":"github.com/dexidp/dex","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2.27.0"}]}],"bundled":2},{"source":"osv","ecosystem":"Go","package":"github.com/russellhaering/goxmldsig","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"1.1.0"}]}],"bundled":2}],"products":[{"vendor":"linuxfoundation","product":"dex"}],"references":[{"url":"https://mattermost.com/blog/coordinated-disclosure-go-xml-vulnerabilities/","tags":["x_refsource_MISC","x_transferred","Vendor Advisory","advisory"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=1907732","tags":["x_refsource_MISC","x_transferred","Issue Tracking","Third Party Advisory","report","web"]},{"url":"https://github.com/dexidp/dex/security/advisories/GHSA-m9hp-7r99-94h5","tags":["x_refsource_MISC","x_transferred","Patch","Third Party Advisory","advisory","fix","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2020-27847","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-2x32-jm95-2cpx"},{"url":"https://github.com/dexidp/dex/releases/tag/v2.27.0","tags":["advisory","web"]},{"url":"https://github.com/mattermost/xml-roundtrip-validator/blob/master/advisories/unstable-attributes.md","tags":["advisory","web"]},{"url":"https://github.com/mattermost/xml-roundtrip-validator/blob/master/advisories/unstable-directives.md","tags":["advisory","web"]},{"url":"https://github.com/mattermost/xml-roundtrip-validator/blob/master/advisories/unstable-elements.md","tags":["advisory","web"]},{"url":"https://github.com/russellhaering/goxmldsig/security/advisories/GHSA-q547-gmf8-8jr7","tags":["advisory","web"]},{"url":"https://github.com/dexidp/dex/commit/324b1c886b407594196113a3dbddebe38eecd4e8","tags":["fix","web"]},{"url":"https://mattermost.com/blog/coordinated-disclosure-go-xml-vulnerabilities","tags":["web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2020-26290","tags":["advisory"]},{"url":"https://github.com/russellhaering/goxmldsig/commit/f6188febf0c29d7ffe26a0436212b19cb9615e64","tags":["web"]},{"url":"https://pkg.go.dev/vuln/GO-2020-0050","tags":["web"]}],"sources":{"cve":[{"id":"CVE-2020-27847","description":"A vulnerability exists in the SAML connector of the github.com/dexidp/dex library used to process SAML Signature Validation. This flaw allows an attacker to bypass SAML authentication. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability. This flaw affects dex versions before 2.27.0.","status":"published","published":"2021-05-28T10:20:35Z","modified":"2024-08-04T16:25:43.583Z","cwes":["CWE-228"],"updated_at":"2026-11-02T14:35:53.552996Z"}],"euvd":[{"id":"EUVD-2021-2428","description":"A vulnerability exists in the SAML connector of the github.com/dexidp/dex library used to process SAML Signature Validation. This flaw allows an attacker to bypass SAML authentication. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability. This flaw affects dex versions before 2.27.0.","status":"published","published":"2021-05-28T10:20:35Z","modified":"2024-08-04T16:25:43Z","updated_at":"2026-11-03T03:07:11.320494Z"}],"ghsa":[{"id":"GHSA-2x32-jm95-2cpx","title":"Authentication Bypass in dex","description":"A vulnerability exists in the SAML connector of the github.com/dexidp/dex library used to process SAML Signature Validation. This flaw allows an attacker to bypass SAML authentication. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability. This flaw affects dex versions before 2.27.0.","status":"published","published":"2021-12-20T17:52:12Z","modified":"2023-02-01T05:06:07Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"cwes":["CWE-228","CWE-290"],"updated_at":"2026-11-02T14:36:37.441118Z"}],"nvd":[{"id":"CVE-2020-27847","description":"A vulnerability exists in the SAML connector of the github.com/dexidp/dex library used to process SAML Signature Validation. This flaw allows an attacker to bypass SAML authentication. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability. This flaw affects dex versions before 2.27.0.","status":"published","published":"2021-05-28T11:15:07.703Z","modified":"2026-06-17T03:09:44.013Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"primary"},{"version":"2.0","score":7.5,"vector":"AV:N/AC:L/Au:N/C:P/I:P/A:P","level":"high","assessor":"primary"}],"cwes":["CWE-228"],"updated_at":"2026-11-02T14:06:43.288951Z"}],"osv":[{"id":"CVE-2020-26290","description":"Dex is a federated OpenID Connect provider written in Go. In Dex before version 2.27.0 there is a critical set of vulnerabilities which impacts users leveraging the SAML connector. The vulnerabilities enables potential signature bypass due to issues with XML encoding in the underlying Go library. The vulnerabilities have been addressed in version 2.27.0 by using the xml-roundtrip-validator from Mattermost (see related references).","status":"published","published":"2020-12-28T20:15:12.493Z","modified":"2026-10-20T10:52:58.155930711Z","cvss":[{"version":"3.1","score":9.6,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H","level":"critical"}],"updated_at":"2026-11-02T15:44:16.248747Z"},{"id":"CVE-2020-27847","description":"A vulnerability exists in the SAML connector of the github.com/dexidp/dex library used to process SAML Signature Validation. This flaw allows an attacker to bypass SAML authentication. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability. This flaw affects dex versions before 2.27.0.","status":"published","published":"2021-05-28T11:15:07.703Z","modified":"2026-10-20T10:53:01.763755324Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"updated_at":"2026-11-02T15:44:16.248747Z"},{"id":"GHSA-2x32-jm95-2cpx","title":"Authentication Bypass in dex","description":"A vulnerability exists in the SAML connector of the github.com/dexidp/dex library used to process SAML Signature Validation. This flaw allows an attacker to bypass SAML authentication. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability. This flaw affects dex versions before 2.27.0.","status":"published","published":"2021-12-20T17:52:12Z","modified":"2026-09-10T03:49:10.072897849Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"cwes":["CWE-228","CWE-290"],"updated_at":"2026-11-02T15:46:35.050232Z"},{"id":"GHSA-m9hp-7r99-94h5","title":"Critical security issues in XML encoding in github.com/dexidp/dex","description":"### Impact\n\nThe following vulnerabilities have been disclosed, which impact users leveraging the SAML connector:\n\nSignature Validation Bypass (CVE-2020-15216): https://github.com/russellhaering/goxmldsig/security/advisories/GHSA-q547-gmf8-8jr7\n\n`encoding/xml` instabilities:\n - [Element namespace prefix instability (CVE-2020-29511)](https://github.com/mattermost/xml-roundtrip-validator/blob/master/advisories/unstable-elements.md)\n - [Attribute namespace prefix instability (CVE-2020-29509)](https://github.com/mattermost/xml-roundtrip-validator/blob/master/advisories/unstable-attributes.md)\n - [Directive comment instability (CVE-2020-29510)](https://github.com/mattermost/xml-roundtrip-validator/blob/master/advisories/unstable-directives.md)\n\n### Patches\n\nImmediately update to [Dex v2.27.0](https://github.com/dexidp/dex/releases/tag/v2.27.0).\n\n### Workarounds\n\nThere are no known workarounds.","status":"published","published":"2021-12-20T17:53:53Z","modified":"2026-09-10T03:49:10.271017587Z","cvss":[{"version":"3.1","score":9.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N","level":"critical"}],"cwes":["CWE-347"],"updated_at":"2026-11-02T15:46:51.811331Z"}]}}