diff --git a/filter/Dockerfile b/filter/Dockerfile
index edac14ac..f296403a 100644
--- a/filter/Dockerfile
+++ b/filter/Dockerfile
@@ -1,5 +1,5 @@
 FROM jwilder/dockerize:0.6.1 AS dockerize
-FROM alpine:3.20
+FROM alpine:3.21
 
 LABEL maintainer="jeff@ressourcenkonflikt.de"
 LABEL vendor="https://github.com/jeboehm/docker-mailserver"
diff --git a/mda/Dockerfile b/mda/Dockerfile
index 47ff252b..629862fb 100644
--- a/mda/Dockerfile
+++ b/mda/Dockerfile
@@ -1,5 +1,5 @@
 FROM jwilder/dockerize:0.6.1 AS dockerize
-FROM alpine:3.20
+FROM alpine:3.21
 
 LABEL maintainer="jeff@ressourcenkonflikt.de"
 LABEL vendor="https://github.com/jeboehm/docker-mailserver"
diff --git a/mta/Dockerfile b/mta/Dockerfile
index ae93bae5..877da0c9 100644
--- a/mta/Dockerfile
+++ b/mta/Dockerfile
@@ -1,5 +1,5 @@
 FROM jwilder/dockerize:0.6.1 AS dockerize
-FROM alpine:3.20
+FROM alpine:3.21
 
 LABEL maintainer="jeff@ressourcenkonflikt.de"
 LABEL vendor="https://github.com/jeboehm/docker-mailserver"
diff --git a/ssl/Dockerfile b/ssl/Dockerfile
index 827d3c7d..d437c436 100644
--- a/ssl/Dockerfile
+++ b/ssl/Dockerfile
@@ -1,4 +1,4 @@
-FROM alpine:3.20
+FROM alpine:3.21
 
 LABEL maintainer="jeff@ressourcenkonflikt.de"
 LABEL vendor="https://github.com/jeboehm/docker-mailserver"
diff --git a/virus/Dockerfile b/virus/Dockerfile
index 282ee600..4968129a 100644
--- a/virus/Dockerfile
+++ b/virus/Dockerfile
@@ -1,4 +1,4 @@
-FROM alpine:3.20
+FROM alpine:3.21
 
 LABEL maintainer="jeff@ressourcenkonflikt.de"
 LABEL vendor="https://github.com/jeboehm/docker-mailserver"
diff --git a/virus/contrib/unofficial-sigs/Dockerfile b/virus/contrib/unofficial-sigs/Dockerfile
index 9d3cffac..68807607 100644
--- a/virus/contrib/unofficial-sigs/Dockerfile
+++ b/virus/contrib/unofficial-sigs/Dockerfile
@@ -1,4 +1,4 @@
-FROM alpine:3.20
+FROM alpine:3.21
 
 LABEL maintainer="jeff@ressourcenkonflikt.de"
 LABEL vendor="https://github.com/jeboehm/docker-mailserver"