diff --git a/Lib/test/test_itertools.py b/Lib/test/test_itertools.py
index 5cb0b0802d4..52a41b5b8ad 100644
--- a/Lib/test/test_itertools.py
+++ b/Lib/test/test_itertools.py
@@ -264,6 +264,11 @@ class TestBasicOps(unittest.TestCase):
                 for proto in range(pickle.HIGHEST_PROTOCOL + 1):
                     self.pickletest(proto, combinations(values, r))      # test pickling
 
+    @support.bigaddrspacetest
+    def test_combinations_overflow(self):
+        with self.assertRaises(OverflowError):
+            combinations("AA", 2**29)
+
         # Test implementation detail:  tuple re-use
     @support.impl_detail("tuple reuse is specific to CPython")
     def test_combinations_tuple_reuse(self):
diff --git a/Misc/NEWS b/Misc/NEWS
index 40c0f015c39..27c0f02bc76 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -229,6 +229,8 @@ Library
 - Issue #23326: Removed __ne__ implementations.  Since fixing default __ne__
   implementation in issue #21408 they are redundant.
 
+- Issue #23366: Fixed possible integer overflow in itertools.combinations.
+
 - Issue #23369: Fixed possible integer overflow in
   _json.encode_basestring_ascii.
 
diff --git a/Modules/itertoolsmodule.c b/Modules/itertoolsmodule.c
index ae5b166561d..b631c352bed 100644
--- a/Modules/itertoolsmodule.c
+++ b/Modules/itertoolsmodule.c
@@ -2359,6 +2359,10 @@ combinations_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
         goto error;
     }
 
+    if (r > PY_SSIZE_T_MAX/sizeof(Py_ssize_t)) {
+        PyErr_SetString(PyExc_OverflowError, "r is too big");
+        goto error;
+    }
     indices = PyMem_Malloc(r * sizeof(Py_ssize_t));
     if (indices == NULL) {
         PyErr_NoMemory();