@@ -142,9 +142,16 @@ def _coerce_to_uint32_array(x):
     else:
         if len(x) == 0:
             return np.array([], dtype=np.uint32)
+        
         # Should be a sequence of interpretable-as-ints. Convert each one to
         # a uint32 array and concatenate.
-        subseqs = [_coerce_to_uint32_array(v) for v in x]
+        subseqs = []
+        for v in x:
+            if hasattr(v, '__len__') and not isinstance(v, str):
+                raise TypeError("SeedSequence does not accept nested sequences.")
+            
+            subseqs.append(_coerce_to_uint32_array(v))
+            
         return np.concatenate(subseqs)
 
 
 
@@ -1,6 +1,11 @@
 import numpy as np
 from numpy.random import SeedSequence
-from numpy.testing import assert_array_compare, assert_array_equal
+from numpy.testing import (
+    assert_array_compare,
+    assert_array_equal,
+    assert_raises,
+    assert_raises_regex,
+)
 
 
 def test_reference_data():
@@ -77,3 +82,22 @@ def test_zero_padding():
         np.not_equal,
         SeedSequence(42, spawn_key=(0,)).generate_state(4),
         expected42)
+
+
+def test_seedsequence_rejects_nested_sequence():
+    with assert_raises(TypeError):
+        SeedSequence(SeedSequence(42))
+
+    # Prevents infinite recursion (Issue #28822) and rejects
+    # invalid types (Issue #27380)
+    match_str = "SeedSequence does not accept nested sequences."
+
+    # Test standard nested lists
+    with assert_raises_regex(TypeError, match_str):
+        SeedSequence([[1, 2], [3, 4]])
+
+    # Test self-referencing/cyclic lists
+    with assert_raises_regex(TypeError, match_str):
+        cyclic_seed = []
+        cyclic_seed.append(cyclic_seed)
+        SeedSequence(cyclic_seed)