diff --git a/python/cloud-run-python-hello-world/requirements.txt b/python/cloud-run-python-hello-world/requirements.txt
index f3d9b380f..3c0cbcf06 100644
--- a/python/cloud-run-python-hello-world/requirements.txt
+++ b/python/cloud-run-python-hello-world/requirements.txt
@@ -1,3 +1,3 @@
-Flask==2.3.3
+Flask==3.1.3
 requests==2.31.0
 debugpy # Required for debugging.
diff --git a/python/python-guestbook/src/backend/requirements.txt b/python/python-guestbook/src/backend/requirements.txt
index ab818773b..97f356811 100644
--- a/python/python-guestbook/src/backend/requirements.txt
+++ b/python/python-guestbook/src/backend/requirements.txt
@@ -1,4 +1,4 @@
-Flask==2.3.3
+Flask==3.1.3
 Flask-PyMongo==2.3.0
 bleach==5.0.1
 debugpy # Required for debugging
diff --git a/python/python-guestbook/src/frontend/requirements.txt b/python/python-guestbook/src/frontend/requirements.txt
index c0f1330a4..a0395b96f 100644
--- a/python/python-guestbook/src/frontend/requirements.txt
+++ b/python/python-guestbook/src/frontend/requirements.txt
@@ -1,4 +1,4 @@
-Flask==2.3.3
+Flask==3.1.3
 requests==2.31.0
 python-dateutil==2.8.2
 debugpy # Required for debugging
diff --git a/python/python-hello-world/src/requirements.txt b/python/python-hello-world/src/requirements.txt
index b8cfcbe2d..b2d136a74 100644
--- a/python/python-hello-world/src/requirements.txt
+++ b/python/python-hello-world/src/requirements.txt
@@ -1,2 +1,2 @@
-Flask==2.3.3
+Flask==3.1.3
 debugpy # Required for debugging