diff --git a/sys/net/application_layer/nanocoap/nanocoap.c b/sys/net/application_layer/nanocoap/nanocoap.c
index 672d31b101..455ebfe7e2 100644
--- a/sys/net/application_layer/nanocoap/nanocoap.c
+++ b/sys/net/application_layer/nanocoap/nanocoap.c
@@ -106,6 +106,11 @@ int coap_parse(coap_pkt_t *pkt, uint8_t *buf, size_t len)
             DEBUG("option count=%u nr=%u len=%i\n", option_count, option_nr, option_len);
 
             if (option_delta) {
+                if (option_count >= NANOCOAP_NOPTS_MAX) {
+                    DEBUG("nanocoap: max nr of options exceeded\n");
+                    return -ENOMEM;
+                }
+
                 optpos->opt_num = option_nr;
                 optpos->offset = (uintptr_t)option_start - (uintptr_t)hdr;
                 DEBUG("optpos option_nr=%u %u\n", (unsigned)option_nr, (unsigned)optpos->offset);
diff --git a/tests/unittests/tests-nanocoap/tests-nanocoap.c b/tests/unittests/tests-nanocoap/tests-nanocoap.c
index 2d0bb1a5c0..38185b2bbd 100644
--- a/tests/unittests/tests-nanocoap/tests-nanocoap.c
+++ b/tests/unittests/tests-nanocoap/tests-nanocoap.c
@@ -15,6 +15,7 @@
 #include <stdint.h>
 #include <stdbool.h>
 #include <string.h>
+#include <stdio.h>
 
 #include "embUnit.h"
 
@@ -433,6 +434,90 @@ static void test_nanocoap__server_reply_simple_con(void)
     TEST_ASSERT_EQUAL_INT(COAP_TYPE_ACK, coap_get_type(&pkt));
 }
 
+static void test_nanocoap__server_option_count_overflow_check(void)
+{
+    /* this test passes a forged CoAP packet containing 42 options (provided by
+     * @nmeum in #10753, 42 is a random number which just needs to be higher
+     * than NANOCOAP_NOPTS_MAX) to coap_parse().  The used coap_pkt_t is part
+     * of a struct, followed by an array of 42 coap_option_t.  The array is
+     * cleared before the call to coap_parse().  If the overflow protection is
+     * working, the array must still be clear after parsing the packet, and the
+     * proper error code (-ENOMEM) is returned.  Otherwise, the parsing wrote
+     * past scratch.pkt, thus the array is not zeroed anymore.
+     */
+
+     static uint8_t pkt_data[] = {
+        0x40, 0x01, 0x09, 0x26, 0x01, 0x17, 0x11, 0x17, 0x11, 0x17, 0x11, 0x17,
+        0x11, 0x17, 0x11, 0x17, 0x11, 0x17, 0x11, 0x17, 0x11, 0x17, 0x11, 0x17,
+        0x11, 0x17, 0x11, 0x17, 0x11, 0x17, 0x11, 0x17, 0x11, 0x17, 0x11, 0x17,
+        0x11, 0x17, 0x11, 0x17, 0x11, 0x17, 0x11, 0x17, 0x11, 0x17, 0x11, 0x17,
+        0x11, 0x17, 0x11, 0x17, 0x11, 0x17, 0x11, 0x17, 0x11, 0x17, 0x11, 0x17,
+        0x11, 0x17, 0x11, 0x17, 0x11, 0x17, 0x11, 0x17, 0x11, 0x17, 0x11, 0x17,
+        0x11, 0x17, 0x11, 0x17, 0x11, 0x17, 0x11, 0x17, 0x11, 0x17, 0x11, 0x17,
+        0x11, 0x17, 0x11, 0x17 };
+
+    /* ensure NANOCOAP_NOPTS_MAX is actually lower than 42 */
+    TEST_ASSERT(NANOCOAP_NOPTS_MAX < 42);
+
+    struct {
+      coap_pkt_t pkt;
+      uint8_t guard_data[42 * sizeof(coap_optpos_t)];
+    } scratch;
+
+    memset(&scratch, 0, sizeof(scratch));
+
+    int res = coap_parse(&scratch.pkt, pkt_data, sizeof(pkt_data));
+
+    /* check if any byte of the guard_data array is non-zero */
+    int dirty = 0;
+    volatile uint8_t *pos = scratch.guard_data;
+    for (size_t i = 0; i < sizeof(scratch.guard_data); i++) {
+        if (*pos) {
+            dirty = 1;
+            break;
+        }
+    }
+
+    TEST_ASSERT_EQUAL_INT(0, dirty);
+    TEST_ASSERT_EQUAL_INT(-ENOMEM, res);
+}
+
+/*
+ * Verifies that coap_parse() recognizes inclusion of too many options.
+ */
+static void test_nanocoap__server_option_count_overflow(void)
+{
+    /* base pkt is a GET for /riot/value, which results in two options for the
+     * path, but only 1 entry in the options array.
+     * Size buf to accept an extra 2-byte option */
+    unsigned base_len = 17;
+    uint8_t buf[17 + (2 * NANOCOAP_NOPTS_MAX)] = {
+        0x42, 0x01, 0xbe, 0x16, 0x35, 0x61, 0xb4, 0x72,
+        0x69, 0x6f, 0x74, 0x05, 0x76, 0x61, 0x6c, 0x75,
+        0x65
+    };
+    coap_pkt_t pkt;
+
+    /* nonsense filler option that contains a single byte of data */
+    uint8_t fill_opt[] = { 0x11, 0x01 };
+
+    /* fill pkt with maximum options; should succeed */
+    int i = 0;
+    for (; i < (2 * (NANOCOAP_NOPTS_MAX - 1)); i+=2) {
+        memcpy(&buf[base_len+i], fill_opt, 2);
+    }
+
+    /* don't read final two bytes, where overflow option will be added later */
+    int res = coap_parse(&pkt, buf, sizeof(buf) - 2);
+    TEST_ASSERT_EQUAL_INT(0, res);
+
+    /* add option to overflow */
+    memcpy(&buf[base_len+i], fill_opt, 2);
+
+    res = coap_parse(&pkt, buf, sizeof(buf));
+    TEST_ASSERT(res < 0);
+}
+
 Test *tests_nanocoap_tests(void)
 {
     EMB_UNIT_TESTFIXTURES(fixtures) {
@@ -450,6 +535,8 @@ Test *tests_nanocoap_tests(void)
         new_TestFixture(test_nanocoap__server_reply_simple),
         new_TestFixture(test_nanocoap__server_get_req_con),
         new_TestFixture(test_nanocoap__server_reply_simple_con),
+        new_TestFixture(test_nanocoap__server_option_count_overflow_check),
+        new_TestFixture(test_nanocoap__server_option_count_overflow),
     };
 
     EMB_UNIT_TESTCALLER(nanocoap_tests, NULL, NULL, fixtures);