When parsing the program name from the incoming log message

from a client, accept all printable characters as being part
of the program name, except ':' and '[', because each is a
possible delimiter.

usr.sbin/syslogd/syslogd.c

@@ -804,7 +804,7 @@ logmsg(int pri, const char *msg, const char *from, int flags)
 
 	/* extract program name */
 	for (i = 0; i < NAME_MAX; i++) {
-		if (!isalnum(msg[i]))
+		if (!isprint(msg[i]) || msg[i] == ':' || msg[i] == '[')
 			break;
 		prog[i] = msg[i];
 	}