{"id":"CVE-2020-27178","aliases":["EUVD-2021-1832","GHSA-q39c-5vh5-vw2p"],"status":"published","title":"Improper Authentication in Apereo CAS","description":"Apereo CAS 5.3.x before 5.3.16, 6.x before 6.1.7.2, 6.2.x before 6.2.4, and 6.3.x before 6.3.0-RC4 mishandles secret keys with Google Authenticator for multifactor authentication.","severity":{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high","assessor":"primary","from":"nvd"},"epss":{"day":"2026-11-09","score":0.01219,"percentile":0.68864,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-287"],"published":"2020-10-16T15:22:48Z","modified":"2026-10-24T10:30:22Z","fixes":[{"ecosystem":"Maven","package":"org.apereo.cas:cas-server-webapp","fixed_in":["5.3.16","6.1.7.2","6.2.4"],"sources":["ghsa","osv"]},{"ecosystem":"Maven","package":"org.apereo.cas:cas-server-support-otp-mfa-core","fixed_in":["5.3.16","6.1.7.2","6.2.4"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"Maven","package":"org.apereo.cas:cas-server-webapp","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.3.0"},{"fixed":"5.3.16"}]}]},{"source":"ghsa","ecosystem":"Maven","package":"org.apereo.cas:cas-server-webapp","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.0.0"},{"last_affected":"6.1.7.1"},{"fixed":"6.1.7.2"}]}]},{"source":"ghsa","ecosystem":"Maven","package":"org.apereo.cas:cas-server-webapp","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.2.4"}]}]},{"source":"ghsa","ecosystem":"Maven","package":"org.apereo.cas:cas-server-support-otp-mfa-core","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.3.0"},{"fixed":"5.3.16"}]}]},{"source":"ghsa","ecosystem":"Maven","package":"org.apereo.cas:cas-server-support-otp-mfa-core","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.0.0"},{"last_affected":"6.1.7.1"},{"fixed":"6.1.7.2"}]}]},{"source":"ghsa","ecosystem":"Maven","package":"org.apereo.cas:cas-server-support-otp-mfa-core","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.2.4"}]}]},{"source":"osv","ecosystem":"Maven","package":"org.apereo.cas:cas-server-webapp","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.3.0"},{"fixed":"5.3.16"}]}],"versions":["5.3.0","5.3.1","5.3.10","5.3.11","5.3.12","5.3.12.1","5.3.13","5.3.14","5.3.15","5.3.15.1","5.3.2","5.3.3","5.3.4","5.3.5","5.3.6","5.3.7","5.3.8","5.3.9"]},{"source":"osv","ecosystem":"Maven","package":"org.apereo.cas:cas-server-webapp","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.0.0"},{"fixed":"6.1.7.2"}]}],"versions":["6.0.0","6.0.1","6.0.2","6.0.3","6.0.4","6.0.5","6.0.5.1","6.0.6","6.0.7","6.0.8","6.0.8.1","6.1.0","6.1.0-RC1","6.1.0-RC2","6.1.0-RC3","6.1.0-RC4","6.1.0-RC5","6.1.0-RC6","6.1.1","6.1.2","6.1.3","6.1.4","6.1.5","6.1.6","6.1.7","6.1.7.1"]},{"source":"osv","ecosystem":"Maven","package":"org.apereo.cas:cas-server-webapp","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.2.4"}]}],"versions":["6.2.0","6.2.1","6.2.2","6.2.3"]},{"source":"osv","ecosystem":"Maven","package":"org.apereo.cas:cas-server-support-otp-mfa-core","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.3.0"},{"fixed":"5.3.16"}]}]},{"source":"osv","ecosystem":"Maven","package":"org.apereo.cas:cas-server-support-otp-mfa-core","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.0.0"},{"fixed":"6.1.7.2"}]}],"versions":["6.0.0","6.0.1","6.0.2","6.0.3","6.0.4","6.0.5","6.0.5.1","6.0.6","6.0.7","6.0.8","6.0.8.1","6.1.0","6.1.0-RC1","6.1.0-RC2","6.1.0-RC3","6.1.0-RC4","6.1.0-RC5","6.1.0-RC6","6.1.1","6.1.2","6.1.3","6.1.4","6.1.5","6.1.6","6.1.7","6.1.7.1"]},{"source":"osv","ecosystem":"Maven","package":"org.apereo.cas:cas-server-support-otp-mfa-core","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.2.4"}]}],"versions":["6.2.0","6.2.1","6.2.2","6.2.3"]}],"products":[{"vendor":"apereo","product":"central_authentication_service"}],"references":[{"url":"https://apereo.github.io/2020/10/14/gauthvuln/","tags":["x_refsource_MISC","x_transferred","Vendor Advisory","advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2020-27178","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-q39c-5vh5-vw2p"},{"url":"https://apereo.github.io/2020/10/14/gauthvuln","tags":["web"]}],"sources":{"cve":[{"id":"CVE-2020-27178","description":"Apereo CAS 5.3.x before 5.3.16, 6.x before 6.1.7.2, 6.2.x before 6.2.4, and 6.3.x before 6.3.0-RC4 mishandles secret keys with Google Authenticator for multifactor authentication.","status":"published","published":"2020-10-16T15:22:48Z","modified":"2024-08-04T16:11:35.538Z","updated_at":"2026-11-02T14:35:53.552996Z"}],"euvd":[{"id":"EUVD-2021-1832","description":"Apereo CAS 5.3.x before 5.3.16, 6.x before 6.1.7.2, 6.2.x before 6.2.4, and 6.3.x before 6.3.0-RC4 mishandles secret keys with Google Authenticator for multifactor authentication.","status":"published","published":"2020-10-16T15:22:48Z","modified":"2024-08-04T16:11:35Z","updated_at":"2026-11-03T03:07:13.515696Z"}],"ghsa":[{"id":"GHSA-q39c-5vh5-vw2p","title":"Improper Authentication in Apereo CAS","description":"Apereo CAS 5.3.x before 5.3.16, 6.x before 6.1.7.2, 6.2.x before 6.2.4, and 6.3.x before 6.3.0-RC4 mishandles secret keys with Google Authenticator for multifactor authentication.","status":"published","published":"2021-08-02T16:47:10Z","modified":"2023-02-01T05:05:50Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high"}],"cwes":["CWE-287"],"updated_at":"2026-11-02T14:36:35.781528Z"}],"nvd":[{"id":"CVE-2020-27178","description":"Apereo CAS 5.3.x before 5.3.16, 6.x before 6.1.7.2, 6.2.x before 6.2.4, and 6.3.x before 6.3.0-RC4 mishandles secret keys with Google Authenticator for multifactor authentication.","status":"published","published":"2020-10-16T16:15:11.573Z","modified":"2026-06-17T03:08:54.417Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high","assessor":"primary"},{"version":"2.0","score":5,"vector":"AV:N/AC:L/Au:N/C:N/I:P/A:N","level":"medium","assessor":"primary"}],"updated_at":"2026-11-02T14:06:19.351389Z"}],"osv":[{"id":"CVE-2020-27178","description":"Apereo CAS 5.3.x before 5.3.16, 6.x before 6.1.7.2, 6.2.x before 6.2.4, and 6.3.x before 6.3.0-RC4 mishandles secret keys with Google Authenticator for multifactor authentication.","status":"published","published":"2020-10-16T16:15:11.573Z","modified":"2026-10-24T10:30:22.290349476Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high"}],"updated_at":"2026-11-02T15:44:16.248747Z"},{"id":"GHSA-q39c-5vh5-vw2p","title":"Improper Authentication in Apereo CAS","description":"Apereo CAS 5.3.x before 5.3.16, 6.x before 6.1.7.2, 6.2.x before 6.2.4, and 6.3.x before 6.3.0-RC4 mishandles secret keys with Google Authenticator for multifactor authentication.","status":"published","published":"2021-08-02T16:47:10Z","modified":"2024-02-17T05:34:53.535717Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high"}],"cwes":["CWE-287"],"updated_at":"2026-11-02T15:46:54.055966Z"}]}}