diff --git a/src/io/HISTORY.md b/src/io/HISTORY.md
index 4be38c37ffc..7482449e210 100644
--- a/src/io/HISTORY.md
+++ b/src/io/HISTORY.md
@@ -4,7 +4,7 @@ IO Utility Change History
 3.10.3
 ------
 
-* No changes.
+* [security] Hardened SWF file by filtering all data passed through ExternalInterface to fix XSS vulnerability.
 
 3.10.2
 ------