CVE-2021-36369: Debian Linux

High severity, CVSS 7.5. EPSS: 1.9% chance of exploitation in the next 30 days.

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.

Affected products

• Debian Debian Linux: version 10.0 only
• Dropbear SSH Project Dropbear SSH: up to and including 2020.81

Published 2022-10-12. Last modified 2026-06-17.