Added changelog for check return of merkle leaf

Signed-off-by: Minos Galanakis <minos.galanakis@arm.com>
diff --git a/ChangeLog.d/1353_lms_check_return_of_merkle_leaf.txt b/ChangeLog.d/1353_lms_check_return_of_merkle_leaf.txt
new file mode 100644
index 0000000..9feca99
--- /dev/null
+++ b/ChangeLog.d/1353_lms_check_return_of_merkle_leaf.txt
@@ -0,0 +1,4 @@
+Security
+   * Fix a vulnerability in LMS verification through which an adversary could
+     get an invalid signature accepted if they could cause a hash accelerator
+     to fail. Found and reported by Linh Le and Ngan Nguyen from Calif.