add a __dict__ descr for IOBase (closes #12878)
diff --git a/Misc/NEWS b/Misc/NEWS
index f489ab2..514d19a 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -28,6 +28,8 @@
 Library
 -------
 
+- Issue #12878: Expose a __dict__ attribute on io.IOBase and its subclasses.
+
 - Issue #12636: IDLE reads the coding cookie when executing a Python script.
 
 - Issue #10946: The distutils commands bdist_dumb, bdist_wininst and bdist_msi