Dropbear is an SSH server and client designed with a small memory footprint.
Multiple vulnerabilities have been discovered in Dropbear. Please review the CVE identifiers referenced below for details.
A remote attacker could possibly execute arbitrary code with root privileges if usernames containing special characters can be created on a system. Also, a dbclient user who can control username or host arguments could potentially run arbitrary code with the privileges of the process.
In addition, a remote attacker could entice a user to process a specially crafted SSH key using dropbearconvert, possibly resulting in execution of arbitrary code with the privileges of the process or a Denial of Service condition.
There is no known workaround at this time.
All Dropbear users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=net-misc/dropbear-2016.74"