It appears there is a remote vulnerability in
exim with the possibility to escalate privileges to root, some details on
http://www.exim.org/lurker/message/20101207.215955.bb32d4f2.en.html. Security teams are currently looking into the issue.
SCNR, but this is your chance to switch to a better
alternative
UPDATE: patch for the buffer overflow (CVE-2010-4344):
http://git.exim.org/exim.git/commitdiff/24c929a27415c7cfc7126c47e4cad39acf3efa6b
A few additional patches will be applied to fix the privilege escalation and other things.