diff --git a/ChangeLog.d/montmul-cmp-branch.txt b/ChangeLog.d/montmul-cmp-branch.txt
new file mode 100644
index 000000000..59945188a
--- /dev/null
+++ b/ChangeLog.d/montmul-cmp-branch.txt
@@ -0,0 +1,6 @@
+Security
+   * Fix a side channel vulnerability in modular exponentiation that could
+     reveal an RSA private key used in a secure enclave. Noticed by Sangho Lee,
+     Ming-Wei Shih, Prasun Gera, Taesoo Kim and Hyesoon Kim (Georgia Institute
+     of Technology); and Marcus Peinado (Microsoft Research). Reported by Raoul
+     Strackx (Fortanix) in #3394.