diff --git a/pyproject.toml b/pyproject.toml
index ba35412e1..170c0ff97 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -24,7 +24,7 @@ cdislogging = "^1.0.0"
 cdispyutils = "^2.0.1"
 flask = ">=3.0.0"
 cryptography = ">=42.0.5"
-flask-cors = ">=5.0.0"
+flask-cors = "<6"
 flask-restful = ">=0.3.8"
 email_validator = "^1.1.1"
 gen3authz = "^1.5.1"