Issue #5386: mmap.write_byte didn't check map size, so it could cause buffer
overrun.
diff --git a/Misc/NEWS b/Misc/NEWS
index 04421f1..0ced972 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -166,6 +166,9 @@
 Library
 -------
 
+- Issue #5386: mmap.write_byte didn't check map size, so it could cause buffer
+  overrun.
+
 - Issue #1533164: Installed but not listed *.pyo was breaking Distutils
   bdist_rpm command.