diff --git a/jupyter-interactive-visualization/requirements.txt b/jupyter-interactive-visualization/requirements.txt
index 1dfd1d0..8caf934 100644
--- a/jupyter-interactive-visualization/requirements.txt
+++ b/jupyter-interactive-visualization/requirements.txt
@@ -1,4 +1,5 @@
 numpy
 plotly
 bokeh
-notebook
\ No newline at end of file
+notebook
+tornado>=6.4.2 # not directly required, pinned by Snyk to avoid a vulnerability
\ No newline at end of file