Add CHANGES and release notes for [GL #4124]

doc/notes/notes-current.rst

@@ -37,6 +37,14 @@ Bug Fixes
 
 - None.
 
+- The value of If-Modified-Since header in statistics channel was not checked
+  for length leading to possible buffer overflow by an authorized user.  We
+  would like to emphasize that statistics channel must be properly setup to
+  allow access only from authorized users of the system. :gl:`#4124`
+
+  This was reported independently by Eric Sesterhenn of X41 D-SEC and Cameron
+  Whitehead.
+
 Known Issues
 ~~~~~~~~~~~~