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Vulnerability record · CVE-2021-36369 · published 12 October 2022

CVE-2021-36369: Dropbear ssh project dropbear ssh improper authentication vulnerability

DDropbear Ssh Project · Dropbear Ssh

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.

7.5 CVSS 3.1 High EPSS 1.5% · top 26.9% CWE-287 · Improper authentication
7.5CVSS 3.1 base score
1.5%EPSS exploitation probability, 30 days
NoNot in CISA KEV
2Affected product versions listed by NVD
8References
17 Jun 2026Last modified by NVD

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.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Affected products

2 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/mkj/dropbear/pull/128 Third Party Advisory
https://github.com/mkj/dropbear/releases Release NotesThird Party Advisory
https://github.com/mkj/dropbear/releases/tag/DROPBEAR_2022.82 Release NotesThird Party Advisory
https://lists.debian.org/debian-lts-announce/2022/11/msg00015.html Mailing ListThird Party Advisory
https://github.com/mkj/dropbear/pull/128 Third Party Advisory
https://github.com/mkj/dropbear/releases Release NotesThird Party Advisory
https://github.com/mkj/dropbear/releases/tag/DROPBEAR_2022.82 Release NotesThird Party Advisory
https://lists.debian.org/debian-lts-announce/2022/11/msg00015.html Mailing ListThird Party Advisory

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2021-36369), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.