{"id":"CVE-2021-36369","aliases":["DEBIAN-CVE-2021-36369","DLA-3187-1","EUVD-2021-22989","GHSA-mwx5-864v-x3jc","MGASA-2022-0436","UBUNTU-CVE-2021-36369","USN-7292-1"],"status":"published","title":"An issue was discovered in Dropbear through 2020.81. Due to a non-RFC-compliant check of the...","description":"An issue was discovered in Dropbear through 2020.81. Due to a non-RFC-compliant check of the available authentication methods in the client-side SSH code, it is possible for an SSH server to change the login process in its favor. This attack can bypass additional security measures such as FIDO2 tokens or SSH-Askpass. Thus, it allows an attacker to abuse a forwarded agent for logging on to another server unnoticed.","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":"2026-11-12","score":0.01864,"percentile":0.79587,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-287"],"published":"2022-10-12T00:00:00Z","modified":"2026-10-23T18:03:16Z","fixes":[{"ecosystem":"Debian:12","package":"dropbear","fixed_in":["2022.82-1"],"sources":["osv"]},{"ecosystem":"Debian:13","package":"dropbear","fixed_in":["2022.82-1"],"sources":["osv"]},{"ecosystem":"Debian:14","package":"dropbear","fixed_in":["2022.82-1"],"sources":["osv"]},{"ecosystem":"Debian:10","package":"dropbear","fixed_in":["2018.76-5+deb10u2"],"sources":["osv"]},{"ecosystem":"Mageia:8","package":"dropbear","fixed_in":["2020.81-1.1.mga8"],"sources":["osv"]},{"ecosystem":"Ubuntu:Pro:18.04:LTS","package":"dropbear","fixed_in":["2017.75-3ubuntu0.1~esm1"],"sources":["osv"]},{"ecosystem":"Ubuntu:Pro:20.04:LTS","package":"dropbear","fixed_in":["2019.78-2ubuntu0.1~esm1"],"sources":["osv"]},{"ecosystem":"Ubuntu:22.04:LTS","package":"dropbear","fixed_in":["2020.81-5ubuntu0.1"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Debian:12","package":"dropbear","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2022.82-1"}]}]},{"source":"osv","ecosystem":"Debian:13","package":"dropbear","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2022.82-1"}]}]},{"source":"osv","ecosystem":"Debian:14","package":"dropbear","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2022.82-1"}]}]},{"source":"osv","ecosystem":"Debian:10","package":"dropbear","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2018.76-5+deb10u2"}]}],"versions":["2018.76-5","2018.76-5+deb10u1"]},{"source":"osv","ecosystem":"Mageia:8","package":"dropbear","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2020.81-1.1.mga8"}]}]},{"source":"osv","ecosystem":"Ubuntu:16.04:LTS","package":"dropbear","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2014.65-1ubuntu2","2015.68-1","2015.70-1","2015.71-1","2016.72-1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:18.04:LTS","package":"dropbear","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2017.75-3ubuntu0.1~esm1"}]}],"versions":["2017.75-2","2017.75-3build1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:20.04:LTS","package":"dropbear","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2019.78-2ubuntu0.1~esm1"}]}],"versions":["2019.78-2build1"]},{"source":"osv","ecosystem":"Ubuntu:22.04:LTS","package":"dropbear","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2020.81-5ubuntu0.1"}]}],"versions":["2020.81-3","2020.81-4","2020.81-5"]},{"source":"osv","ecosystem":"Ubuntu:Pro:18.04:LTS","package":"dropbear","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2017.75-3ubuntu0.1~esm1"}]}],"versions":["2017.75-2","2017.75-3build1"],"bundled":2},{"source":"osv","ecosystem":"Ubuntu:Pro:20.04:LTS","package":"dropbear","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2019.78-2ubuntu0.1~esm1"}]}],"versions":["2019.78-2build1"],"bundled":2},{"source":"osv","ecosystem":"Ubuntu:22.04:LTS","package":"dropbear","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2020.81-5ubuntu0.1"}]}],"versions":["2020.81-3","2020.81-4","2020.81-5"],"bundled":2}],"products":[{"vendor":"debian","product":"debian_linux"},{"vendor":"dropbear_ssh_project","product":"dropbear_ssh"}],"references":[{"url":"https://github.com/mkj/dropbear/pull/128","tags":["x_transferred","Third Party Advisory","advisory","web","report"]},{"url":"https://github.com/mkj/dropbear/releases","tags":["x_transferred","Release Notes","Third Party Advisory","advisory","report"]},{"url":"https://github.com/mkj/dropbear/releases/tag/DROPBEAR_2022.82","tags":["x_transferred","Release Notes","Third Party Advisory","advisory","report"]},{"url":"https://lists.debian.org/debian-lts-announce/2022/11/msg00015.html","tags":["mailing-list","x_transferred","Mailing List","Third Party Advisory","advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-36369"},{"url":"https://github.com/advisories/GHSA-mwx5-864v-x3jc"},{"url":"https://security-tracker.debian.org/tracker/CVE-2021-36369","tags":["advisory"]},{"url":"https://advisories.mageia.org/MGASA-2022-0436.html","tags":["advisory"]},{"url":"https://bugs.mageia.org/show_bug.cgi?id=31119","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2021-36369","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2021-36369","tags":["report"]},{"url":"https://ubuntu.com/security/notices/USN-7292-1","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2023-48795","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2021-36369","description":"An issue was discovered in Dropbear through 2020.81. Due to a non-RFC-compliant check of the available authentication methods in the client-side SSH code, it is possible for an SSH server to change the login process in its favor. This attack can bypass additional security measures such as FIDO2 tokens or SSH-Askpass. Thus, it allows an attacker to abuse a forwarded agent for logging on to another server unnoticed.","status":"published","published":"2022-10-12T00:00:00Z","modified":"2025-05-15T18:45:40.651Z","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":"adp"}],"cwes":["CWE-287"],"updated_at":"2026-11-02T14:33:05.989686Z"}],"euvd":[{"id":"EUVD-2021-22989","description":"An issue was discovered in Dropbear through 2020.81. Due to a non-RFC-compliant check of the available authentication methods in the client-side SSH code, it is possible for an SSH server to change the login process in its favor. This attack can bypass additional security measures such as FIDO2 tokens or SSH-Askpass. Thus, it allows an attacker to abuse a forwarded agent for logging on to another server unnoticed.","status":"published","published":"2022-10-12T00:00:00Z","modified":"2025-05-15T18:45:40Z","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":"2026-11-02T20:32:46.094311Z"}],"ghsa":[{"id":"GHSA-mwx5-864v-x3jc","title":"An issue was discovered in Dropbear through 2020.81. Due to a non-RFC-compliant check of the...","description":"An issue was discovered in Dropbear through 2020.81. Due to a non-RFC-compliant check of the available authentication methods in the client-side SSH code, it is possible for an SSH server to change the login process in its favor. This attack can bypass additional security measures such as FIDO2 tokens or SSH-Askpass. Thus, it allows an attacker to abuse a forwarded agent for logging on to another server unnoticed.","status":"published","published":"2022-10-13T12:00:27Z","modified":"2023-02-03T05:00:51Z","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":"2026-11-02T14:52:51.988629Z"}],"nvd":[{"id":"CVE-2021-36369","description":"An issue was discovered in Dropbear through 2020.81. Due to a non-RFC-compliant check of the available authentication methods in the client-side SSH code, it is possible for an SSH server to change the login process in its favor. This attack can bypass additional security measures such as FIDO2 tokens or SSH-Askpass. Thus, it allows an attacker to abuse a forwarded agent for logging on to another server unnoticed.","status":"published","published":"2022-10-12T21:15:09.493Z","modified":"2026-06-17T03:58:45.52Z","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":"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":"secondary"}],"cwes":["CWE-287"],"updated_at":"2026-11-02T14:07:06.906968Z"}],"osv":[{"id":"CVE-2021-36369","description":"An issue was discovered in Dropbear through 2020.81. Due to a non-RFC-compliant check of the available authentication methods in the client-side SSH code, it is possible for an SSH server to change the login process in its favor. This attack can bypass additional security measures such as FIDO2 tokens or SSH-Askpass. Thus, it allows an attacker to abuse a forwarded agent for logging on to another server unnoticed.","status":"published","published":"2022-10-12T21:15:09.493Z","modified":"2026-10-20T10:53:50.703206098Z","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":"2026-11-02T15:44:20.434873Z"},{"id":"DEBIAN-CVE-2021-36369","description":"An issue was discovered in Dropbear through 2020.81. Due to a non-RFC-compliant check of the available authentication methods in the client-side SSH code, it is possible for an SSH server to change the login process in its favor. This attack can bypass additional security measures such as FIDO2 tokens or SSH-Askpass. Thus, it allows an attacker to abuse a forwarded agent for logging on to another server unnoticed.","status":"published","published":"2022-10-12T21:15:09.493Z","modified":"2026-10-23T18:03:16.156778162Z","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":"2026-11-02T15:45:35.233346Z"},{"id":"UBUNTU-CVE-2021-36369","description":"An issue was discovered in Dropbear through 2020.81. Due to a non-RFC-compliant check of the available authentication methods in the client-side SSH code, it is possible for an SSH server to change the login process in its favor. This attack can bypass additional security measures such as FIDO2 tokens or SSH-Askpass. Thus, it allows an attacker to abuse a forwarded agent for logging on to another server unnoticed.","status":"published","published":"2022-10-12T21:15:00Z","modified":"2026-02-04T02:48:04.882358Z","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"},{"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":"2026-11-02T15:54:27.870979Z"},{"id":"DLA-3187-1","title":"dropbear - security update","status":"published","published":"2022-11-14T00:00:00Z","modified":"2026-03-09T01:20:21.884311Z","updated_at":"2026-11-02T15:46:11.734021Z"},{"id":"MGASA-2022-0436","title":"Updated dropbear packages fix security vulnerability","description":"Updated dropbear package fixes a security vulnerability in dbclient:.\nDue to a non-RFC-compliant check of the available authentication methods\nin the client-side SSH code, it is possible for an SSH server to change\nthe login process in its favor. This attack can bypass additional security\nmeasures such as FIDO2 tokens or SSH-Askpass. Thus, it allows an attacker\nto abuse a forwarded agent for logging on to another server unnoticed.\n\nThe fix adds a new option, DisableTrivialAuth, to dbclient to disable this\nattack vector. Invoke dbclient as\n\"dbclient -o DisableTrivialAuth=yes localhost …\" to enable this mitigation\non each dbclient invocation.\n","status":"published","published":"2022-11-24T22:21:24Z","modified":"2026-04-16T04:42:38.38182306Z","updated_at":"2026-11-02T15:49:42.263076Z"},{"id":"USN-7292-1","title":"Several security issues were fixed in Dropbear","description":"Manfred Kaiser discovered that Dropbear through 2020.81 does not properly\ncheck the available authentication methods in the client-side SSH code.\nAn attacker could use this vulnerability to gain unauthorized access to\nremote systems. (CVE-2021-36369)\n\nFabian Bäumer, Marcus Brinkmann, and Jörg Schwenk discovered that the SSH\ntransport protocol implementation in Dropbear had weak integrity checks.\nAn attacker could use this vulnerability to bypass security features\nlike encryption and integrity checks. (CVE-2023-48795)\n","status":"published","published":"2025-02-25T12:33:22Z","modified":"2026-04-27T17:45:09.194609Z","updated_at":"2026-11-02T16:58:18.876384Z"}]}}