Avahi: "netlink" message vulnerability

Background

Avahi is a system that facilitates service discovery on a local network.

Description

Avahi does not check that the netlink messages come from the kernel instead of a user-space process.

Impact

A local attacker could exploit this vulnerability by crafting malicious netlink messages and trick Avahi to react to fake network changes. This could lead users to connect to untrusted services without knowing.

Workaround

There is no known workaround at this time.

Resolution

All Avahi users should upgrade to the latest version:

 # emerge --sync
 # emerge --ask --oneshot --verbose ">=net-dns/avahi-0.6.15"