diff --git a/ChangeLog b/ChangeLog
index 1672bdf07..0af86c0c8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
 mbed TLS ChangeLog (Sorted per branch, date)
 
+= mbed TLS 1.3.21 released xxxx-xx-xx
+
+Security
+   * Fix unsafe bounds check in ssl_parse_client_psk_identity() when adding
+     64kB to the address of the SSL buffer wraps around.
+
 = mbed TLS 1.3.20 released 2017-06-21
 
 Security