diff --git a/batch/cpp_application/application/Dockerfile b/batch/cpp_application/application/Dockerfile
index d174ed97..63929ae8 100644
--- a/batch/cpp_application/application/Dockerfile
+++ b/batch/cpp_application/application/Dockerfile
@@ -14,7 +14,7 @@
 
 # We chose Alpine to build the image because it has good support for creating
 # statically-linked, small programs.
-FROM alpine:3.20 AS build
+FROM alpine:3.21 AS build
 
 # Install the typical development tools for C++, and
 # the base OS headers and libraries.
diff --git a/batch/parallel/application/Dockerfile b/batch/parallel/application/Dockerfile
index 3c0fd176..2d7a240f 100644
--- a/batch/parallel/application/Dockerfile
+++ b/batch/parallel/application/Dockerfile
@@ -14,7 +14,7 @@
 
 # We chose Alpine to build the image because it has good support for creating
 # statically-linked, small programs.
-FROM alpine:3.20 AS build
+FROM alpine:3.21 AS build
 
 # Install the typical development tools for C++, and
 # the base OS headers and libraries.
diff --git a/cloud-run-hello-world/Dockerfile b/cloud-run-hello-world/Dockerfile
index fdd691a4..b417ea12 100644
--- a/cloud-run-hello-world/Dockerfile
+++ b/cloud-run-hello-world/Dockerfile
@@ -16,7 +16,7 @@
 # [START dockerfile]
 # We chose Alpine to build the image because it has good support for creating
 # statically-linked, small programs.
-FROM alpine:3.20 AS build
+FROM alpine:3.21 AS build
 
 # Install the typical development tools for C++, and
 # the base OS headers and libraries.