diff --git a/docker/Dockerfile.linux.386 b/docker/Dockerfile.linux.386
index 940952c..5df7b20 100644
--- a/docker/Dockerfile.linux.386
+++ b/docker/Dockerfile.linux.386
@@ -1,4 +1,4 @@
-FROM i386/alpine:3.20@sha256:ee8f671d10ed605c1ea81df90f411e136c9b104a8e07520638b8cab46fce2311 AS build
+FROM i386/alpine:3.21@sha256:7b0f18085272db228a5b32fd67f4de1e9690bfae60990971bdb0a324347e2401 AS build
 RUN apk add --no-cache ca-certificates mailcap
 
 FROM scratch
diff --git a/docker/Dockerfile.linux.amd64 b/docker/Dockerfile.linux.amd64
index b21276f..bc138d5 100644
--- a/docker/Dockerfile.linux.amd64
+++ b/docker/Dockerfile.linux.amd64
@@ -1,4 +1,4 @@
-FROM amd64/alpine:3.20@sha256:b53b9310c8cfdecd161bbe589b167fd4338d342c6d4ecad0fd1f5d32b390b99f AS build
+FROM amd64/alpine:3.21@sha256:9a64a732c12ebe63a5b85832ea1b032bd7c4fde32ff89af7897d3e3fc334f33e AS build
 RUN apk add --no-cache ca-certificates mailcap
 
 FROM scratch
diff --git a/docker/Dockerfile.linux.arm b/docker/Dockerfile.linux.arm
index c578f47..d503547 100644
--- a/docker/Dockerfile.linux.arm
+++ b/docker/Dockerfile.linux.arm
@@ -1,4 +1,4 @@
-FROM arm32v6/alpine:3.20@sha256:a2b9c479c72b128baaee28fb9db735a98dc3d8bc9e2dbbedeaebb55a37d48566 AS build
+FROM arm32v6/alpine:3.21@sha256:9eb920e2ac62ae9ded9d084180d2f112823f8d4bcece2d13c5afdec326454100 AS build
 RUN apk add --no-cache ca-certificates mailcap
 
 FROM scratch
diff --git a/docker/Dockerfile.linux.arm64 b/docker/Dockerfile.linux.arm64
index 971cb31..5b2874a 100644
--- a/docker/Dockerfile.linux.arm64
+++ b/docker/Dockerfile.linux.arm64
@@ -1,4 +1,4 @@
-FROM arm64v8/alpine:3.20@sha256:7d206216871a9feecd6c6689d895889577fdcb28f3f789d8243b3a12f38a2730 AS build
+FROM arm64v8/alpine:3.21@sha256:cbcd3d242c2e582539d1fa51cf1fa550387be5baec96b0799c0010f96ec1f354 AS build
 RUN apk add --no-cache ca-certificates mailcap
 
 FROM scratch