fixed possible RCE vulnerability, unset escape variable (default tilde) stops consider "~" char after new-line as composing escape sequence

closes GHSA-m985-3f3v-cwmm for 0.9

config/action.d/complain.conf

@@ -79,7 +79,7 @@ logpath = /dev/null
 # Notes.:  Your system mail command. Is passed 2 args: subject and recipient
 # Values:  CMD
 #
-mailcmd = mail -s
+mailcmd = mail -E 'set escape' -s
 
 # Option:  mailargs
 # Notes.:  Additional arguments to mail command. e.g. for standard Unix mail:

config/action.d/dshield.conf

@@ -176,7 +176,7 @@ tcpflags =
 # Notes.:  Your system mail command. Is passed 2 args: subject and recipient
 # Values:  CMD
 #
-mailcmd = mail -s
+mailcmd = mail -E 'set escape' -s
 
 # Option:  mailargs
 # Notes.:  Additional arguments to mail command. e.g. for standard Unix mail:

config/action.d/mail-buffered.conf

@@ -14,7 +14,7 @@ actionstart = printf %%b "Hi,\n
               The jail <name> has been started successfully.\n
               Output will be buffered until <lines> lines are available.\n
               Regards,\n
-              Fail2Ban"|mail -s "[Fail2Ban] <name>: started on `uname -n`" <dest>
+              Fail2Ban"|mail -E 'set escape' -s "[Fail2Ban] <name>: started on `uname -n`" <dest>
 
 # Option:  actionstop
 # Notes.:  command executed once at the end of Fail2Ban
@@ -25,13 +25,13 @@ actionstop = if [ -f <tmpfile> ]; then
                  These hosts have been banned by Fail2Ban.\n
                  `cat <tmpfile>`
                  Regards,\n
-                 Fail2Ban"|mail -s "[Fail2Ban] <name>: Summary from `uname -n`" <dest>
+                 Fail2Ban"|mail -E 'set escape' -s "[Fail2Ban] <name>: Summary from `uname -n`" <dest>
                  rm <tmpfile>
              fi
              printf %%b "Hi,\n
              The jail <name> has been stopped.\n
              Regards,\n
-             Fail2Ban"|mail -s "[Fail2Ban] <name>: stopped on `uname -n`" <dest>
+             Fail2Ban"|mail -E 'set escape' -s "[Fail2Ban] <name>: stopped on `uname -n`" <dest>
 
 # Option:  actioncheck
 # Notes.:  command executed once before each actionban command
@@ -52,7 +52,7 @@ actionban = printf %%b "`date`: <ip> (<failures> failures)\n" >> <tmpfile>
                 These hosts have been banned by Fail2Ban.\n
                 `cat <tmpfile>`
                 \nRegards,\n
-                Fail2Ban"|mail -s "[Fail2Ban] <name>: Summary" <dest>
+                Fail2Ban"|mail -E 'set escape' -s "[Fail2Ban] <name>: Summary" <dest>
                 rm <tmpfile>
             fi
 

config/action.d/mail-whois-lines.conf

@@ -17,7 +17,7 @@ before = mail-whois-common.conf
 actionstart = printf %%b "Hi,\n
               The jail <name> has been started successfully.\n
               Regards,\n
-              Fail2Ban"|mail -s "[Fail2Ban] <name>: started on `uname -n`" <dest>
+              Fail2Ban" | <mailcmd> "[Fail2Ban] <name>: started on `uname -n`" <dest>
 
 # Option:  actionstop
 # Notes.:  command executed once at the end of Fail2Ban
@@ -26,7 +26,7 @@ actionstart = printf %%b "Hi,\n
 actionstop = printf %%b "Hi,\n
              The jail <name> has been stopped.\n
              Regards,\n
-             Fail2Ban"|mail -s "[Fail2Ban] <name>: stopped on `uname -n`" <dest>
+             Fail2Ban" | <mailcmd> "[Fail2Ban] <name>: stopped on `uname -n`" <dest>
 
 # Option:  actioncheck
 # Notes.:  command executed once before each actionban command
@@ -48,7 +48,7 @@ actionban = printf %%b "Hi,\n
             Lines containing IP:<ip> in <logpath>\n
             `grep -E <grepopts> '(^|[^0-9])<ip>([^0-9]|$)' <logpath>`\n\n
             Regards,\n
-            Fail2Ban"|mail -s "[Fail2Ban] <name>: banned <ip> from  `uname -n`" <dest>
+            Fail2Ban" | <mailcmd> "[Fail2Ban] <name>: banned <ip> from  `uname -n`" <dest>
 
 # Option:  actionunban
 # Notes.:  command executed when unbanning an IP. Take care that the
@@ -60,6 +60,12 @@ actionunban =
 
 [Init]
 
+# Option:  mailcmd
+# Notes.:  Your system mail command. Is passed 2 args: subject and recipient
+# Values:  CMD
+#
+mailcmd = mail -E 'set escape' -s
+
 # Default name of the chain
 #
 name = default

config/action.d/mail-whois.conf

@@ -17,7 +17,7 @@ before = mail-whois-common.conf
 actionstart = printf %%b "Hi,\n
               The jail <name> has been started successfully.\n
               Regards,\n
-              Fail2Ban"|mail -s "[Fail2Ban] <name>: started on `uname -n`" <dest>
+              Fail2Ban"|mail -E 'set escape' -s "[Fail2Ban] <name>: started on `uname -n`" <dest>
 
 # Option:  actionstop
 # Notes.:  command executed once at the end of Fail2Ban
@@ -26,7 +26,7 @@ actionstart = printf %%b "Hi,\n
 actionstop = printf %%b "Hi,\n
              The jail <name> has been stopped.\n
              Regards,\n
-             Fail2Ban"|mail -s "[Fail2Ban] <name>: stopped on `uname -n`" <dest>
+             Fail2Ban"|mail -E 'set escape' -s "[Fail2Ban] <name>: stopped on `uname -n`" <dest>
 
 # Option:  actioncheck
 # Notes.:  command executed once before each actionban command
@@ -46,7 +46,7 @@ actionban = printf %%b "Hi,\n
             Here is more information about <ip> :\n
             `%(_whois_command)s`\n
             Regards,\n
-            Fail2Ban"|mail -s "[Fail2Ban] <name>: banned <ip> from `uname -n`" <dest>
+            Fail2Ban"|mail -E 'set escape' -s "[Fail2Ban] <name>: banned <ip> from `uname -n`" <dest>
 
 # Option:  actionunban
 # Notes.:  command executed when unbanning an IP. Take care that the

config/action.d/mail.conf

@@ -13,7 +13,7 @@
 actionstart = printf %%b "Hi,\n
               The jail <name> has been started successfully.\n
               Regards,\n
-              Fail2Ban"|mail -s "[Fail2Ban] <name>: started  on `uname -n`" <dest>
+              Fail2Ban"|mail -E 'set escape' -s "[Fail2Ban] <name>: started  on `uname -n`" <dest>
 
 # Option:  actionstop
 # Notes.:  command executed once at the end of Fail2Ban
@@ -22,7 +22,7 @@ actionstart = printf %%b "Hi,\n
 actionstop = printf %%b "Hi,\n
              The jail <name> has been stopped.\n
              Regards,\n
-             Fail2Ban"|mail -s "[Fail2Ban] <name>: stopped on `uname -n`" <dest>
+             Fail2Ban"|mail -E 'set escape' -s "[Fail2Ban] <name>: stopped on `uname -n`" <dest>
 
 # Option:  actioncheck
 # Notes.:  command executed once before each actionban command
@@ -40,7 +40,7 @@ actionban = printf %%b "Hi,\n
             The IP <ip> has just been banned by Fail2Ban after
             <failures> attempts against <name>.\n
             Regards,\n
-            Fail2Ban"|mail -s "[Fail2Ban] <name>: banned <ip> from `uname -n`" <dest>
+            Fail2Ban"|mail -E 'set escape' -s "[Fail2Ban] <name>: banned <ip> from `uname -n`" <dest>
 
 # Option:  actionunban
 # Notes.:  command executed when unbanning an IP. Take care that the