[3.13] gh-145506: Fixes CVE-2026-2297 by ensuring SourcelessFileLoader uses io.open_code (GH-145507)

(cherry picked from commit a51b1b5)

Co-authored-by: Steve Dower <steve.dower@python.org>

Author: miss-islington

Lib/importlib/_bootstrap_external.py

@@ -1210,7 +1210,7 @@ def get_filename(self, fullname):
 
     def get_data(self, path):
         """Return the data from path as raw bytes."""
-        if isinstance(self, (SourceLoader, ExtensionFileLoader)):
+        if isinstance(self, (SourceLoader, SourcelessFileLoader, ExtensionFileLoader)):
             with _io.open_code(str(path)) as file:
                 return file.read()
         else:

Misc/NEWS.d/next/Security/2026-03-04-18-59-17.gh-issue-145506.6hwvEh.rst

@@ -0,0 +1,2 @@
+Fixes :cve:`2026-2297` by ensuring that ``SourcelessFileLoader`` uses
+:func:`io.open_code` when opening ``.pyc`` files.