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libs/checkpoint-sqlite/tests/test_sqlite.py

@@ -243,3 +243,59 @@ class TestSqliteSaver:
 
             with pytest.raises(ValueError, match="Invalid filter key"):
                 list(saver.list(None, filter={malicious_key: "dummy"}))
+
+    def test_limit_parameter_sql_injection_prevention(self) -> None:
+        """Test that the limit parameter properly uses parameterized queries to prevent SQL injection."""
+        with SqliteSaver.from_conn_string(":memory:") as saver:
+            # Setup: Create multiple checkpoints
+            for i in range(5):
+                config: RunnableConfig = {
+                    "configurable": {
+                        "thread_id": f"thread-{i}",
+                        "checkpoint_ns": "",
+                    }
+                }
+                checkpoint = empty_checkpoint()
+                metadata: CheckpointMetadata = {"index": i}
+                saver.put(config, checkpoint, metadata, {})
+
+            # Test that limit works correctly with valid integer
+            results = list(saver.list(None, limit=2))
+            assert len(results) == 2
+
+            # Test that limit=0 returns no results
+            results = list(saver.list(None, limit=0))
+            assert len(results) == 0
+
+            # Test that limit=None returns all results
+            results = list(saver.list(None, limit=None))
+            assert len(results) == 5
+
+            # Test explicit SQL injection attempt via limit parameter
+            # Even if type checking is bypassed and a malicious string is passed,
+            # the parameterized query will treat it as a value, not SQL code
+            # This would cause an error (can't convert string to int for LIMIT),
+            # which is the correct secure behavior
+            malicious_limits = [
+                "1; DROP TABLE checkpoints; --",
+                "1 OR 1=1",
+                "999999 UNION SELECT * FROM checkpoints",
+            ]
+
+            for malicious_limit in malicious_limits:
+                # The parameterized query should safely reject non-integer limits
+                # or convert them in a way that prevents SQL injection
+                try:
+                    # Bypass type checking by casting
+                    results = list(saver.list(None, limit=malicious_limit))  # type: ignore
+                    # If it doesn't raise an error, it should at least not execute the injection
+                    # SQLite's parameter binding will try to convert the string to an integer
+                    # which will either fail or treat it as 0
+                except Exception:
+                    # Expected: SQLite should reject invalid limit values
+                    pass
+
+            # Verify the checkpoints table still exists and has all data
+            # (would have been dropped if injection succeeded)
+            results = list(saver.list(None, limit=None))
+            assert len(results) == 5