If specific usernames including "%" symbols can be created on a system
(validated by getpwnam()) then an attacker could run arbitrary code as root
when connecting to Dropbear server.
A dbclient user who can control username or host arguments could potentially
run arbitrary code as the dbclient user. This could be a problem if scripts
or webpages pass untrusted input to the dbclient program.
dropbearconvert import of OpenSSH keys could run arbitrary code as
the local dropbearconvert user when parsing malicious key files.
dbclient could run arbitrary code as the local dbclient user if
particular -m or -c arguments are provided. This could be an issue where
dbclient is used in scripts.
dbclient or dropbear server could expose process memory to the
running user if compiled with DEBUG_TRACE and running with -v