Advisories » MGASA-2022-0436

Updated dropbear packages fix security vulnerability

Publication date: 24 Nov 2022
Type: security
Affected Mageia releases : 8
CVE: CVE-2021-36369


Updated dropbear package fixes a security vulnerability in dbclient:.
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.

The fix adds a new option, DisableTrivialAuth, to dbclient to disable this
attack vector. Invoke dbclient as
"dbclient -o DisableTrivialAuth=yes localhost …" to enable this mitigation
on each dbclient invocation.