diff --git a/docs/requirements.txt b/docs/requirements.txt
index f5f3d0a0..80c435a5 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -9,4 +9,5 @@ furo
 analytics-python
 token-bucket
 sphinx-autobuild
-sphinx-autodoc-typehints
\ No newline at end of file
+sphinx-autodoc-typehints
+tornado>=6.4.1 # not directly required, pinned by Snyk to avoid a vulnerability
\ No newline at end of file