diff --git a/core/Dockerfile b/core/Dockerfile
index 65a13e0..886305f 100644
--- a/core/Dockerfile
+++ b/core/Dockerfile
@@ -1,6 +1,6 @@
 # syntax = docker/dockerfile:1.3
 # Use 3.15 for Core since it has Python 3.9
-FROM alpine:3.19
+FROM alpine:3.20
 
 # Add requirements file.
 COPY requirements.txt /tmp/
@@ -15,7 +15,6 @@ RUN --mount=type=cache,target=/root/.cache \
     && apk add --no-cache bash su-exec postgresql-client mysql-client curl python3 py3-pip linux-headers py-cryptography mariadb-connector-c lynx tzdata \
     && python3 -m pip install --break-system-packages -U pip setuptools wheel \
         && python3 -m pip install --break-system-packages psycopg2 \
-                   gunicorn==19.9.0 \
                    pymysql \
                    -r /tmp/requirements.txt \
                    'importlib-resources<6.0.0' \
diff --git a/core/Dockerfile.dev b/core/Dockerfile.dev
index 7064e34..37f2da9 100644
--- a/core/Dockerfile.dev
+++ b/core/Dockerfile.dev
@@ -1,6 +1,6 @@
 # syntax = docker/dockerfile:1.3
 # Use 3.15 for Core since it has Python 3.9
-FROM alpine:3.19
+FROM alpine:3.20
 
 # Set the commits that we are building.
 ARG CORE_REF
@@ -18,7 +18,6 @@ RUN --mount=type=cache,target=/root/.cache \
     && python3 -m pip install --break-system-packages \
         git+https://gitlab.com/mailman/mailman \
         git+https://gitlab.com/mailman/mailman-hyperkitty \
-        gunicorn==19.9.0 \
     && apk del build-deps \
     && adduser -S mailman