diff --git a/lower-constraints.txt b/lower-constraints.txt
index 582a30f29..36ff4fe7e 100644
--- a/lower-constraints.txt
+++ b/lower-constraints.txt
@@ -26,7 +26,7 @@ extras==1.0.0
 fasteners==0.14.1
 fixtures==3.0.0
 flake8==2.5.5
-Flask==0.10
+Flask==0.12.3
 future==0.16.0
 futurist==1.6.0
 greenlet==0.4.13
diff --git a/requirements.txt b/requirements.txt
index 9a55d205f..6bd41d4f3 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -3,7 +3,7 @@
 # process, which may cause wedges in the gate later.
 
 cotyledon>=1.3.0 # Apache-2.0
-Flask!=0.11,>=0.10 # BSD
+Flask!=0.11,>=0.12.3 # BSD
 kuryr-lib>=0.5.0 # Apache-2.0
 pbr!=2.1.0,>=2.0.0 # Apache-2.0
 requests>=2.14.2 # Apache-2.0