BUG: use uuid4 instead of md5 for fake column in cross merge (#48029)

* BUG: use usedforsecurity for md5 in cross merge

* BUG: use usedforsecurity for md5 in cross merge

* Use uuid

Author: phofl

Diff for: doc/source/whatsnew/v1.5.0.rst

@@ -1095,6 +1095,7 @@ Reshaping
 - Bug in :func:`concat` not sorting the column names when ``None`` is included (:issue:`47331`)
 - Bug in :func:`concat` with identical key leads to error when indexing :class:`MultiIndex` (:issue:`46519`)
 - Bug in :func:`pivot_table` raising ``TypeError`` when ``dropna=True`` and aggregation column has extension array dtype (:issue:`47477`)
+- Bug in :func:`merge` raising error for ``how="cross"`` when using ``FIPS`` mode in ssl library (:issue:`48024`)
 - Bug in :meth:`DataFrame.join` with a list when using suffixes to join DataFrames with duplicate column names (:issue:`46396`)
 - Bug in :meth:`DataFrame.pivot_table` with ``sort=False`` results in sorted index (:issue:`17041`)
 - Bug in :meth:`concat` when ``axis=1`` and ``sort=False`` where the resulting Index was a :class:`Int64Index` instead of a :class:`RangeIndex` (:issue:`46675`)

Diff for: pandas/core/reshape/merge.py

@@ -6,13 +6,13 @@
 import copy
 import datetime
 from functools import partial
-import hashlib
 import string
 from typing import (
     TYPE_CHECKING,
     Hashable,
     cast,
 )
+import uuid
 import warnings
 
 import numpy as np
@@ -1311,7 +1311,7 @@ def _create_cross_configuration(
             DataFrames with cross_col, the merge operation set to inner and the column
             to join over.
         """
-        cross_col = f"_cross_{hashlib.md5().hexdigest()}"
+        cross_col = f"_cross_{uuid.uuid4()}"
         how = "inner"
         return (
             left.assign(**{cross_col: 1}),