diff --git a/CHANGES.md b/CHANGES.md
index 6686cafa5..ab6fce3e7 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,10 +1,13 @@
 Synapse 1.10.0rc1 (2020-01-31)
 ==============================
 
+**WARNING**: As of this release Synapse validates `client_secret` parameters in the Client-Server API as per the spec. See [\#6766](https://github.com/matrix-org/synapse/issues/6766) for details.
+
+
 Features
 --------
 
-- Implement updated authorization rules for aliases events, from [MSC2260](https://github.com/matrix-org/matrix-doc/pull/2260). ([\#6787](https://github.com/matrix-org/synapse/issues/6787), [\#6790](https://github.com/matrix-org/synapse/issues/6790), [\#6794](https://github.com/matrix-org/synapse/issues/6794))
+- Add experimental support for updated authorization rules for aliases events, from [MSC2260](https://github.com/matrix-org/matrix-doc/pull/2260). ([\#6787](https://github.com/matrix-org/synapse/issues/6787), [\#6790](https://github.com/matrix-org/synapse/issues/6790), [\#6794](https://github.com/matrix-org/synapse/issues/6794))
 
 
 Bugfixes