mtr combines the functionality of the 'traceroute' and 'ping' programs in a single network diagnostic tool.
Adam Zabrocki reported a boundary error within the split_redraw() function in the file split.c, possibly leading to a stack-based buffer overflow.
A remote attacker could use a specially crafted resolved hostname to execute arbitrary code with root privileges. However, it is required that the attacker controls the DNS server used by the victim, and that the "-p" (or "--split") command line option is used.
There is no known workaround at this time.
All mtr users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=net-analyzer/mtr-0.73-r1"