Hi,

if we assume for simplicity that every relay running Linux that has not
rebooted since 2016-02-16 is vulnerable to CVE-2015-7547, than these are
the current stats (optimistic, because we assume that everyone that
rebooted did also update).

Vulnerable relays:

+------------+------------------+-----------------+
| cwfraction | guardprobability | exitprobability |
+------------+------------------+-----------------+
|      0.586 |            0.639 |           0.518 |
+------------+------------------+-----------------+
(1=100%)

Apply patches and reboot.

Debian
https://www.debian.org/security/2016/dsa-3481

RHEL/CentOS
https://rhn.redhat.com/errata/RHSA-2016-0176.html

Ubuntu
http://www.ubuntu.com/usn/usn-2900-1/