diff --git a/appengine/standard_python3/pubsub/requirements.txt b/appengine/standard_python3/pubsub/requirements.txt
index ca2c80071d9..0d1351d311e 100644
--- a/appengine/standard_python3/pubsub/requirements.txt
+++ b/appengine/standard_python3/pubsub/requirements.txt
@@ -1,4 +1,4 @@
-Flask==2.1.0
+Flask==2.3.2
 google-api-python-client==2.47.0
 google-auth==2.6.2
 google-cloud-pubsub==2.9.0