--- /dev/null
+Security fix for CVE-2016-1531
+==============================
+
+All installations having Exim set-uid root and using 'perl_startup' are
+vulnerable to a local privilege escalation. Any user who can start an
+instance of Exim (and this is normally *any* user) can gain root
+privileges.
+
+New options
+-----------
+
+We had to introduce two new configuration options:
+
+ keep_environment =
+ add_environment =
+
+Both options are empty per default. That is, Exim cleans the complete
+environment on startup. This affects Exim itself and any subprocesses,
+as transports, that may call other programs via some alias mechanisms,
+as routers (queryprogram), lookups, and so on.
+
+** THIS MAY BREAK your existing installation **
+
+If both options are not used in the configuration, Exim issues a warning
+on startup. This warning disappears if at least one of these options is
+used (even if set to an empty value).
+
+keep_environment should contain a list of trusted environment variables.
+(Do you trust PATH?). This may be a list of names and REs.
+
+ keep_environment = ^LDAP_ : FOO_PATH
+
+To add (or override) variables, you can use add_environment:
+
+ add_environment = <; PATH=/sbin:/usr/sbin
+
+
+New behaviour
+-------------
+
+Now Exim changes it's working directory to / right after startup,
+even before reading it's configuration. (Later Exim changes it's working
+directory to $spool_directory, as usual.)
+
+Exim only accepts an absolute configuration file path now, when using
+the -C option.
+
+
+Thank you for your understanding.