diff --git a/ALPINE.txt b/ALPINE.txt
index 55b698c77..f29702326 100644
--- a/ALPINE.txt
+++ b/ALPINE.txt
@@ -1 +1 @@
-3.18
\ No newline at end of file
+3.21
\ No newline at end of file
diff --git a/Dockerfile b/Dockerfile
index 4ad3d88d9..7a5dbce5a 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -62,7 +62,7 @@ RUN GOARCH=$TARGETARCH go install -ldflags="\
       -X tailscale.com/version.gitCommitStamp=$VERSION_GIT_HASH" \
       -v ./cmd/tailscale ./cmd/tailscaled ./cmd/containerboot
 
-FROM alpine:3.18
+FROM alpine:3.21
 RUN apk add --no-cache ca-certificates iptables iproute2 ip6tables
 
 COPY --from=build-env /go/bin/* /usr/local/bin/
diff --git a/Dockerfile.base b/Dockerfile.base
index eb4f0a02a..5186746a4 100644
--- a/Dockerfile.base
+++ b/Dockerfile.base
@@ -1,5 +1,5 @@
 # Copyright (c) Tailscale Inc & AUTHORS
 # SPDX-License-Identifier: BSD-3-Clause
 
-FROM alpine:3.18
+FROM alpine:3.21
 RUN apk add --no-cache ca-certificates iptables iproute2 ip6tables iputils