diff --git a/Misc/ACKS b/Misc/ACKS
index b5c3dc6..089e463 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -417,6 +417,7 @@
 Damon Kohler
 Joseph Koshy
 Maksim Kozyarchuk
+Stefan Krah
 Bob Kras
 Holger Krekel
 Michael Kremer
diff --git a/Misc/NEWS b/Misc/NEWS
index 9225c6f..66748ef 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -12,6 +12,11 @@
 Core and Builtins
 -----------------
 
+- Issue #5677: Explicitly forbid write operations on read-only file objects,
+  and read operations on write-only file objects.  On Windows, the system C
+  library would return a bogus result; on Solaris, it was possible to crash
+  the interpreter.  Patch by Stefan Krah.
+
 - Issue #7853: Normalize exceptions before they are passed to a context managers
   __exit__ method.