diff --git a/CHANGES b/CHANGES
index 33c580c4d5..ad6bf8c09f 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,6 @@
+4318.	[security]	Malformed control messages can trigger assertions
+			in named and rndc. (CVE-2016-1285) [RT #41666]
+
 4317.	[bug]		Age all unused servers on fetch timeout. [RT #41597]
 
 4316.	[func]		Add option to tools to print RRs in unknown
diff --git a/bin/named/control.c b/bin/named/control.c
index 76cddb7b3c..75fc278334 100644
--- a/bin/named/control.c
+++ b/bin/named/control.c
@@ -91,7 +91,7 @@ ns_control_docommand(isccc_sexpr_t *message, isc_boolean_t readonly,
 #endif
 
 	data = isccc_alist_lookup(message, "_data");
-	if (data == NULL) {
+	if (!isccc_alist_alistp(data)) {
 		/*
 		 * No data section.
 		 */
diff --git a/bin/named/controlconf.c b/bin/named/controlconf.c
index ae24d5ef94..5495f56770 100644
--- a/bin/named/controlconf.c
+++ b/bin/named/controlconf.c
@@ -405,7 +405,7 @@ control_recvmessage(isc_task_t *task, isc_event_t *event) {
 	 * Limit exposure to replay attacks.
 	 */
 	_ctrl = isccc_alist_lookup(request, "_ctrl");
-	if (_ctrl == NULL) {
+	if (!isccc_alist_alistp(_ctrl)) {
 		log_invalid(&conn->ccmsg, ISC_R_FAILURE);
 		goto cleanup_request;
 	}
diff --git a/bin/rndc/rndc.c b/bin/rndc/rndc.c
index 707d9c70bf..80bcf46315 100644
--- a/bin/rndc/rndc.c
+++ b/bin/rndc/rndc.c
@@ -279,8 +279,8 @@ rndc_recvdone(isc_task_t *task, isc_event_t *event) {
 	   isccc_cc_fromwire(&source, &response, algorithm, &secret));
 
 	data = isccc_alist_lookup(response, "_data");
-	if (data == NULL)
-		fatal("no data section in response");
+	if (!isccc_alist_alistp(data))
+		fatal("bad or missing data section in response");
 	result = isccc_cc_lookupstring(data, "err", &errormsg);
 	if (result == ISC_R_SUCCESS) {
 		failed = ISC_TRUE;
@@ -353,8 +353,8 @@ rndc_recvnonce(isc_task_t *task, isc_event_t *event) {
 	   isccc_cc_fromwire(&source, &response, algorithm, &secret));
 
 	_ctrl = isccc_alist_lookup(response, "_ctrl");
-	if (_ctrl == NULL)
-		fatal("_ctrl section missing");
+	if (!isccc_alist_alistp(_ctrl))
+		fatal("bad or missing ctrl section in response");
 	nonce = 0;
 	if (isccc_cc_lookupuint32(_ctrl, "_nonce", &nonce) != ISC_R_SUCCESS)
 		nonce = 0;
diff --git a/doc/arm/notes.xml b/doc/arm/notes.xml
index 282b315bbb..e37696c085 100644
--- a/doc/arm/notes.xml
+++ b/doc/arm/notes.xml
@@ -167,7 +167,15 @@
 	  This flaw is disclosed in CVE-2015-8705. [RT #41397]
 	</para>
       </listitem>
+      <listitem>
+	<para>
+	  Malformed control messages can trigger assertions in named
+	  and rndc. This flaw is disclosed in CVE-2016-1285. [RT
+	  #41666]
+	</para>
+      </listitem>
     </itemizedlist>
+
   </section>
   <section xml:id="relnotes_features"><info><title>New Features</title></info>
 
diff --git a/lib/isccc/cc.c b/lib/isccc/cc.c
index 9759b40f9b..6d95e3dfd8 100644
--- a/lib/isccc/cc.c
+++ b/lib/isccc/cc.c
@@ -422,13 +422,13 @@ verify(isccc_sexpr_t *alist, unsigned char *data, unsigned int length,
 	 * Extract digest.
 	 */
 	_auth = isccc_alist_lookup(alist, "_auth");
-	if (_auth == NULL)
+	if (!isccc_alist_alistp(_auth))
 		return (ISC_R_FAILURE);
 	if (algorithm == ISCCC_ALG_HMACMD5)
 		hmac = isccc_alist_lookup(_auth, "hmd5");
 	else
 		hmac = isccc_alist_lookup(_auth, "hsha");
-	if (hmac == NULL)
+	if (!isccc_sexpr_binaryp(hmac))
 		return (ISC_R_FAILURE);
 	/*
 	 * Compute digest.
@@ -745,7 +745,7 @@ isccc_cc_createack(isccc_sexpr_t *message, isc_boolean_t ok,
 	REQUIRE(ackp != NULL && *ackp == NULL);
 
 	_ctrl = isccc_alist_lookup(message, "_ctrl");
-	if (_ctrl == NULL ||
+	if (!isccc_alist_alistp(_ctrl) ||
 	    isccc_cc_lookupuint32(_ctrl, "_ser", &serial) != ISC_R_SUCCESS ||
 	    isccc_cc_lookupuint32(_ctrl, "_tim", &t) != ISC_R_SUCCESS)
 		return (ISC_R_FAILURE);
@@ -789,7 +789,7 @@ isccc_cc_isack(isccc_sexpr_t *message) {
 	isccc_sexpr_t *_ctrl;
 
 	_ctrl = isccc_alist_lookup(message, "_ctrl");
-	if (_ctrl == NULL)
+	if (!isccc_alist_alistp(_ctrl))
 		return (ISC_FALSE);
 	if (isccc_cc_lookupstring(_ctrl, "_ack", NULL) == ISC_R_SUCCESS)
 		return (ISC_TRUE);
@@ -801,7 +801,7 @@ isccc_cc_isreply(isccc_sexpr_t *message) {
 	isccc_sexpr_t *_ctrl;
 
 	_ctrl = isccc_alist_lookup(message, "_ctrl");
-	if (_ctrl == NULL)
+	if (!isccc_alist_alistp(_ctrl))
 		return (ISC_FALSE);
 	if (isccc_cc_lookupstring(_ctrl, "_rpl", NULL) == ISC_R_SUCCESS)
 		return (ISC_TRUE);
@@ -821,7 +821,7 @@ isccc_cc_createresponse(isccc_sexpr_t *message, isccc_time_t now,
 
 	_ctrl = isccc_alist_lookup(message, "_ctrl");
 	_data = isccc_alist_lookup(message, "_data");
-	if (_ctrl == NULL || _data == NULL ||
+	if (!isccc_alist_alistp(_ctrl) || !isccc_alist_alistp(_data) ||
 	    isccc_cc_lookupuint32(_ctrl, "_ser", &serial) != ISC_R_SUCCESS ||
 	    isccc_cc_lookupstring(_data, "type", &type) != ISC_R_SUCCESS)
 		return (ISC_R_FAILURE);
@@ -1002,7 +1002,7 @@ isccc_cc_checkdup(isccc_symtab_t *symtab, isccc_sexpr_t *message,
 	isccc_sexpr_t *_ctrl;
 
 	_ctrl = isccc_alist_lookup(message, "_ctrl");
-	if (_ctrl == NULL ||
+	if (!isccc_alist_alistp(_ctrl) ||
 	    isccc_cc_lookupstring(_ctrl, "_ser", &_ser) != ISC_R_SUCCESS ||
 	    isccc_cc_lookupstring(_ctrl, "_tim", &_tim) != ISC_R_SUCCESS)
 		return (ISC_R_FAILURE);