CVE-2021-36369

Name: CVE-2021-36369
Creator: NVD / NIST
Published: 2022-10-12T21:15:09.493+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 1.35%

Last modified Jun 17, 2026

CVE-2021-36369 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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. EPSS estimates a 1.35% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

7.5/10

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

EPSS Probability

1.35%

67.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Dropbear Ssh Project	Dropbear Ssh	<= 2020.81
Debian	Debian Linux	10.0

References

https://github.com/mkj/dropbear/pull/128Third Party Advisory
https://github.com/mkj/dropbear/releasesRelease Notes, Third Party Advisory
https://github.com/mkj/dropbear/releases/tag/DROPBEAR_2022.82Release Notes, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2022/11/msg00015.htmlMailing List, Third Party Advisory
https://github.com/mkj/dropbear/pull/128Third Party Advisory
https://github.com/mkj/dropbear/releasesRelease Notes, Third Party Advisory
https://github.com/mkj/dropbear/releases/tag/DROPBEAR_2022.82Release Notes, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2022/11/msg00015.htmlMailing List, Third Party Advisory

Timeline

Published: Oct 12, 2022
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-36369?

How severe is CVE-2021-36369?

CVE-2021-36369 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 1.35% probability of exploitation in the next 30 days.

How do I fix CVE-2021-36369?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-36369?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST