--- dropbear-0.52/svr-authpubkeyoptions.c.orig	2008-11-11 15:09:03.000000000 +0100
+++ dropbear-0.52/svr-authpubkeyoptions.c	2009-12-29 13:28:04.000000000 +0100
@@ -152,6 +152,17 @@
 			ses.authstate.pubkey_options->no_pty_flag = 1;
 			goto next_option;
 		}
+		if (match_option(options_buf, "from=\"") == DROPBEAR_SUCCESS) {
+			while (options_buf->pos < options_buf->len) {
+				const char c = buf_getbyte(options_buf);
+				if (c == '"') {
+					dropbear_log(LOG_WARNING, "unknown option from= ignored");
+					goto next_option;
+				}
+			}
+			dropbear_log(LOG_WARNING, "Badly formatted from= authorized_keys option");
+			goto bad_option;
+		}
 		if (match_option(options_buf, "command=\"") == DROPBEAR_SUCCESS) {
 			int escaped = 0;
 			const unsigned char* command_start = buf_getptr(options_buf, 0);