diff --git a/dev/Dockerfile b/dev/Dockerfile
index 74fbc7f4..fd030416 100644
--- a/dev/Dockerfile
+++ b/dev/Dockerfile
@@ -11,7 +11,7 @@
 #   docker build -f dev/Dockerfile.alpine   -t rook:e2e-alpine .
 # =============================================================================
 
-FROM ubuntu:24.04
+FROM ubuntu:26.04@sha256:f144425ff09be612d6d9ad965196e9cdc23dae1f42110a8a11a3e9a8198759f7
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
     ca-certificates \
diff --git a/dev/Dockerfile.test-client b/dev/Dockerfile.test-client
index d913b6ac..cb0f48f3 100644
--- a/dev/Dockerfile.test-client
+++ b/dev/Dockerfile.test-client
@@ -10,7 +10,7 @@
 #   docker compose -f dev/docker-compose.test.yml up -d
 # =============================================================================
 
-FROM ubuntu:24.04
+FROM ubuntu:26.04@sha256:f144425ff09be612d6d9ad965196e9cdc23dae1f42110a8a11a3e9a8198759f7
 
 # Prevent interactive prompts during package installation
 ENV DEBIAN_FRONTEND=noninteractive