diff --git a/docs/requirements.txt b/docs/requirements.txt
index 3cae86b8..28c104ed 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -16,3 +16,4 @@ pysolr
 nbformat>=4.2.0
 numpy>=1.22.2 # not directly required, pinned by Snyk to avoid a vulnerability
 zipp>=3.19.1 # not directly required, pinned by Snyk to avoid a vulnerability
+tornado>=6.4.2 # not directly required, pinned by Snyk to avoid a vulnerability