Clarify bug scenario in Changlog
diff --git a/ChangeLog b/ChangeLog
index 28ae0b3..7a710bd 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,9 +2,11 @@
= mbed TLS 2.x.x branch released xxxx-xx-xx
-Changes
+Bugfix
* Fix possible memory leak in mbedtls_ssl_config_free().
- by junyeonLEE <dlwnsdus2@naver.com>
+ This can occur only if the user doesn't use mbedtls_ssl_conf_psk() and
+ instead incorrectly manipulates conf->psk and/or conf->psk_identity
+ directly. Fix submitted by junyeonLEE.
= mbed TLS 2.7.x branch released 2018-xx-xx