diff --git a/flask-api/pyproject.toml b/flask-api/pyproject.toml
index 91e387407..de74fd5d0 100644
--- a/flask-api/pyproject.toml
+++ b/flask-api/pyproject.toml
@@ -96,7 +96,7 @@ dependencies = [
     "prance==23.6.21.0",
     # marshmallow is used to define database model schema, to enable easy serialization
     # of models to and from json. 
-    "marshmallow==3.20.1",
+    "marshmallow==3.26.2",
     "marshmallow_sqlalchemy==1.0.0",
     "openapi-spec-validator==0.6.0",
 
diff --git a/flask-api/requirements-dev.txt b/flask-api/requirements-dev.txt
index c62b30316..dad6830aa 100644
--- a/flask-api/requirements-dev.txt
+++ b/flask-api/requirements-dev.txt
@@ -112,7 +112,7 @@ markupsafe==2.1.5
     #   jinja2
     #   mako
     #   werkzeug
-marshmallow==3.20.1
+marshmallow==3.26.2
     # via
     #   homeuniteus-api (pyproject.toml)
     #   marshmallow-sqlalchemy
diff --git a/flask-api/requirements.txt b/flask-api/requirements.txt
index e5e2890b1..6981f46c3 100644
--- a/flask-api/requirements.txt
+++ b/flask-api/requirements.txt
@@ -72,7 +72,7 @@ markupsafe==2.1.5
     #   jinja2
     #   mako
     #   werkzeug
-marshmallow==3.20.1
+marshmallow==3.26.2
     # via
     #   homeuniteus-api (pyproject.toml)
     #   marshmallow-sqlalchemy