diff --git a/Dockerfile b/Dockerfile
index 4a556f7..6c06130 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,6 +1,6 @@
 # syntax=docker/dockerfile:1
 
-FROM ghcr.io/linuxserver/baseimage-alpine-nginx:3.20
+FROM ghcr.io/linuxserver/baseimage-alpine-nginx:3.21
 
 # set version label
 ARG BUILD_DATE
diff --git a/Dockerfile.aarch64 b/Dockerfile.aarch64
index 8c7cfcb..3ff07dc 100644
--- a/Dockerfile.aarch64
+++ b/Dockerfile.aarch64
@@ -1,6 +1,6 @@
 # syntax=docker/dockerfile:1
 
-FROM ghcr.io/linuxserver/baseimage-alpine-nginx:arm64v8-3.20
+FROM ghcr.io/linuxserver/baseimage-alpine-nginx:arm64v8-3.21
 
 # set version label
 ARG BUILD_DATE
diff --git a/readme-vars.yml b/readme-vars.yml
index c75a9b8..3b7114c 100644
--- a/readme-vars.yml
+++ b/readme-vars.yml
@@ -116,6 +116,7 @@ init_diagram: |
   "cops:latest" <- Base Images
 # changelog
 changelogs:
+  - {date: "16.12.24:", desc: "Rebase to Alpine 3.21."}
   - {date: "24.09.24:", desc: "Existing users should verify: site-confs/default.conf - Update rewriting rules default site conf."}
   - {date: "14.09.24:", desc: "Ensure user config files have the right permissions."}
   - {date: "09.09.24:", desc: "In COPS 3.x, the config_local.php is being moved over to config/local.php and this container will automatically migrate it. Existing users should verify: config_local.php and/or config/local.php - define $config['cops_kepubify_path'] if they want to use it"}