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UBUNTU-CVE-2021-36369 High

UBUNTU-CVE-2021-36369

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.

Exploit probability Not scored
Published October 12, 2022
Required by Not available
Last source change February 4, 2026

02 / AFFECTED SOFTWARE

Affected packages

Ubuntu:16.04:LTS dropbear

5 explicit affected versions

Ubuntu:22.04:LTS dropbear

3 explicit affected versions

Ubuntu:Pro:18.04:LTS dropbear

2 explicit affected versions

Ubuntu:Pro:20.04:LTS dropbear

1 explicit affected versions

03 / CONNECTIONS

Connected vulnerabilities

04 / EVIDENCE

Source records

Open Source Vulnerabilities UBUNTU-CVE-2021-36369

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.

View original source

05 / REFERENCES

Further evidence