Vulnerability identifier: #VU79726

Vulnerability risk: Medium

CVSSv3.1: 4.7 [CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-36369

CWE-ID: CWE-287

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Dropbear
Server applications / Remote management servers, RDP, SSH

Vendor: Matt Johnston

Description

The vulnerability allows a remote user to bypass authentication process.

The vulnerability exists due to a non-RFC-compliant check of the available authentication methods in the client-side SSH code. A remote user can bypass additional security measures such as FIDO2 tokens or SSH-Askpass and abuse a forwarded agent for logging on to another server unnoticed.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Dropbear: 2011.54 - 2020.81

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External links
http://github.com/mkj/dropbear/pull/128
http://github.com/mkj/dropbear/releases/tag/DROPBEAR_2022.82
http://lists.debian.org/debian-lts-announce/2022/11/msg00015.html

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.