diff --git a/2025-05-17-16-45-00.gh-issue-134070.vdhoke.rst b/2025-05-17-16-45-00.gh-issue-134070.vdhoke.rst
new file mode 100644
index 00000000000000..267bcef668f339
--- /dev/null
+++ b/2025-05-17-16-45-00.gh-issue-134070.vdhoke.rst
@@ -0,0 +1,4 @@
+.. gh-issue: 134070
+.. section: Core and Builtins
+
+Fixed an out-of-bounds read in the generic implementation of `mi_clz32` and `mi_ctz32` in the integrated mimalloc allocator. This bug could occur on platforms with 64-bit `unsigned long` values. Based on upstream fix from microsoft/mimalloc.
diff --git a/Lib/tempfile.py b/Lib/tempfile.py
index cadb0bed3cce3b..6ba64accd2b3bd 100644
--- a/Lib/tempfile.py
+++ b/Lib/tempfile.py
@@ -356,7 +356,7 @@ def mkstemp(suffix=None, prefix=None, dir=None, text=False):
 
     return _mkstemp_inner(dir, prefix, suffix, flags, output_type)
 
-
+# TODO: Suggest AppContainer mkdtemp fix
 def mkdtemp(suffix=None, prefix=None, dir=None):
     """User-callable function to create and return a unique temporary
     directory.  The return value is the pathname of the directory.
diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2025-05-17-16-45-00.gh-issue-134070.vdhoke.rst b/Misc/NEWS.d/next/Core_and_Builtins/2025-05-17-16-45-00.gh-issue-134070.vdhoke.rst
new file mode 100644
index 00000000000000..7346e68350b526
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2025-05-17-16-45-00.gh-issue-134070.vdhoke.rst
@@ -0,0 +1,4 @@
+.. gh-issue: 134070
+.. section: Core and Builtins
+
+Fixed an out-of-bounds read in the generic implementation of ``mi_clz32`` and ``mi_ctz32`` in the integrated mimalloc allocator. This bug could occur on platforms with 64-bit ``unsigned long`` values. Based on upstream fix from microsoft/mimalloc.