diff --git a/nimble/host/src/ble_sm.c b/nimble/host/src/ble_sm.c
index 67e8728de..d6527d4f0 100644
--- a/nimble/host/src/ble_sm.c
+++ b/nimble/host/src/ble_sm.c
@@ -1487,9 +1487,12 @@ ble_sm_pair_req_rx(uint16_t conn_handle, uint8_t op, struct os_mbuf **om,
         if (conn->bhc_flags & BLE_HS_CONN_F_MASTER) {
             res->sm_err = BLE_SM_ERR_CMD_NOT_SUPP;
             res->app_status = BLE_HS_SM_US_ERR(BLE_SM_ERR_CMD_NOT_SUPP);
-        } else if (!ble_sm_pair_cmd_is_valid(&req)) {
+        } else if (req.max_enc_key_size < BLE_SM_PAIR_KEY_SZ_MIN) {
+            res->sm_err = BLE_SM_ERR_ENC_KEY_SZ;
+            res->app_status = BLE_HS_SM_US_ERR(BLE_SM_ERR_ENC_KEY_SZ);
+        } else if (req.max_enc_key_size > BLE_SM_PAIR_KEY_SZ_MAX) {
             res->sm_err = BLE_SM_ERR_INVAL;
-            res->app_status =  BLE_HS_SM_US_ERR(BLE_SM_ERR_INVAL);
+            res->app_status = BLE_HS_SM_US_ERR(BLE_SM_ERR_INVAL);
         } else {
             res->execute = 1;
         }
@@ -1520,7 +1523,10 @@ ble_sm_pair_rsp_rx(uint16_t conn_handle, uint8_t op, struct os_mbuf **om,
     proc = ble_sm_proc_find(conn_handle, BLE_SM_PROC_STATE_PAIR, 1, &prev);
     if (proc != NULL) {
         proc->pair_rsp = rsp;
-        if (!ble_sm_pair_cmd_is_valid(&rsp)) {
+        if (rsp.max_enc_key_size < BLE_SM_PAIR_KEY_SZ_MIN) {
+            res->sm_err = BLE_SM_ERR_ENC_KEY_SZ;
+            res->app_status = BLE_HS_SM_US_ERR(BLE_SM_ERR_ENC_KEY_SZ);
+        } else if (rsp.max_enc_key_size > BLE_SM_PAIR_KEY_SZ_MAX) {
             res->sm_err = BLE_SM_ERR_INVAL;
             res->app_status = BLE_HS_SM_US_ERR(BLE_SM_ERR_INVAL);
         } else {
diff --git a/nimble/host/src/ble_sm_cmd.c b/nimble/host/src/ble_sm_cmd.c
index e438c023b..67fa1b098 100644
--- a/nimble/host/src/ble_sm_cmd.c
+++ b/nimble/host/src/ble_sm_cmd.c
@@ -90,26 +90,6 @@ ble_sm_pair_cmd_parse(void *payload, int len, struct ble_sm_pair_cmd *cmd)
     cmd->resp_key_dist = u8ptr[5];
 }
 
-int
-ble_sm_pair_cmd_is_valid(struct ble_sm_pair_cmd *cmd)
-{
-    if (cmd->io_cap >= BLE_SM_IO_CAP_RESERVED) {
-        return 0;
-    }
-
-    if (cmd->oob_data_flag >= BLE_SM_PAIR_OOB_RESERVED) {
-        return 0;
-    }
-
-    if (cmd->max_enc_key_size < BLE_SM_PAIR_KEY_SZ_MIN ||
-        cmd->max_enc_key_size > BLE_SM_PAIR_KEY_SZ_MAX) {
-
-        return 0;
-    }
-
-    return 1;
-}
-
 void
 ble_sm_pair_cmd_write(void *payload, int len, int is_req,
                       struct ble_sm_pair_cmd *cmd)
@@ -143,7 +123,6 @@ ble_sm_pair_cmd_tx(uint16_t conn_handle, int is_req,
     ble_sm_pair_cmd_write(txom->om_data, txom->om_len, is_req, cmd);
     BLE_SM_LOG_CMD(1, is_req ? "pair req" : "pair rsp", conn_handle,
                    ble_sm_pair_cmd_log, cmd);
-    BLE_HS_DBG_ASSERT(ble_sm_pair_cmd_is_valid(cmd));
 
     rc = ble_sm_tx(conn_handle, txom);
     if (rc != 0) {
diff --git a/nimble/host/src/ble_sm_lgcy.c b/nimble/host/src/ble_sm_lgcy.c
index ddc666de9..a77671e32 100644
--- a/nimble/host/src/ble_sm_lgcy.c
+++ b/nimble/host/src/ble_sm_lgcy.c
@@ -65,12 +65,16 @@ ble_sm_lgcy_io_action(struct ble_sm_proc *proc)
 {
     int action;
 
-    if (proc->pair_req.oob_data_flag && proc->pair_rsp.oob_data_flag) {
+    if (proc->pair_req.oob_data_flag == BLE_SM_PAIR_OOB_YES &&
+        proc->pair_rsp.oob_data_flag == BLE_SM_PAIR_OOB_YES) {
         action = BLE_SM_IOACT_OOB;
     } else if (!(proc->pair_req.authreq & BLE_SM_PAIR_AUTHREQ_MITM) &&
                !(proc->pair_rsp.authreq & BLE_SM_PAIR_AUTHREQ_MITM)) {
 
         action = BLE_SM_IOACT_NONE;
+    } else if (proc->pair_req.io_cap >= BLE_SM_IO_CAP_RESERVED ||
+               proc->pair_rsp.io_cap >= BLE_SM_IO_CAP_RESERVED) {
+        action = BLE_SM_IOACT_NONE;
     } else if (proc->flags & BLE_SM_PROC_F_INITIATOR) {
         action = ble_sm_lgcy_init_ioa[proc->pair_rsp.io_cap]
                                      [proc->pair_req.io_cap];
diff --git a/nimble/host/src/ble_sm_sc.c b/nimble/host/src/ble_sm_sc.c
index 11b29a1c8..f8a698305 100644
--- a/nimble/host/src/ble_sm_sc.c
+++ b/nimble/host/src/ble_sm_sc.c
@@ -112,12 +112,16 @@ ble_sm_sc_io_action(struct ble_sm_proc *proc)
 {
     int action;
 
-    if (proc->pair_req.oob_data_flag || proc->pair_rsp.oob_data_flag) {
+    if (proc->pair_req.oob_data_flag == BLE_SM_PAIR_OOB_YES ||
+        proc->pair_rsp.oob_data_flag == BLE_SM_PAIR_OOB_YES) {
         action = BLE_SM_IOACT_OOB;
     } else if (!(proc->pair_req.authreq & BLE_SM_PAIR_AUTHREQ_MITM) &&
                !(proc->pair_rsp.authreq & BLE_SM_PAIR_AUTHREQ_MITM)) {
 
         action = BLE_SM_IOACT_NONE;
+    } else if (proc->pair_req.io_cap >= BLE_SM_IO_CAP_RESERVED ||
+               proc->pair_rsp.io_cap >= BLE_SM_IO_CAP_RESERVED) {
+        action = BLE_SM_IOACT_NONE;
     } else if (proc->flags & BLE_SM_PROC_F_INITIATOR) {
         action = ble_sm_sc_init_ioa[proc->pair_rsp.io_cap]
                                    [proc->pair_req.io_cap];