diff --git a/ChangeLog b/ChangeLog
index 16982a0e0..ee020ab04 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,6 +2,12 @@ mbed TLS ChangeLog (Sorted per branch, date)
 
 = mbed TLS 2.7.x branch released xxxx-xx-xx
 
+Security
+   * Fix side channel vulnerability in ECDSA key generation. Obtaining precise
+     timings on the comparison in the key generation enabled the attacker to
+     learn leading bits of the ephemeral key used during ECDSA signatures and to
+     recover the private key.
+
 Changes
    * Add unit tests for AES-GCM when called through mbedtls_cipher_auth_xxx()
      from the cipher abstraction layer. Fixes #2198.