diff --git a/binder/requirements.txt b/binder/requirements.txt
index 7a5b0416ea9..697945a6640 100644
--- a/binder/requirements.txt
+++ b/binder/requirements.txt
@@ -19,3 +19,4 @@ kaleido
 scikit-learn
 umap-learn
 wget
+tornado>=6.4.2 # not directly required, pinned by Snyk to avoid a vulnerability