Exim 4.72 and earlier allows local users to gain privileges by leveraging the ability of the exim user account to specify an alternate configuration file with a directive that contains arbitrary commands, as demonstrated by the spool_directory directive.
https://bugzilla.redhat.com/show_bug.cgi?id=662012
http://www.ubuntu.com/usn/USN-1060-1
http://www.theregister.co.uk/2010/12/11/exim_code_execution_peril/
http://www.openwall.com/lists/oss-security/2021/05/04/7
http://www.metasploit.com/modules/exploit/unix/smtp/exim4_string_format
http://www.kb.cert.org/vuls/id/758489
http://www.exim.org/lurker/message/20101207.215955.bb32d4f2.en.html
http://www.debian.org/security/2011/dsa-2154
http://www.debian.org/security/2010/dsa-2131
http://openwall.com/lists/oss-security/2010/12/10/1
http://lists.opensuse.org/opensuse-security-announce/2010-12/msg00003.html
http://lists.exim.org/lurker/message/20101210.164935.385e04d0.en.html
http://lists.exim.org/lurker/message/20101209.172233.abcba158.en.html