diff --git a/.github/workflows/build.yaml b/.github/workflows/build.yaml
index e717951..696704a 100644
--- a/.github/workflows/build.yaml
+++ b/.github/workflows/build.yaml
@@ -21,7 +21,7 @@ jobs:
         uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6
 
       - name: Log in to Container Registry
-        uses: docker/login-action@v3
+        uses: docker/login-action@c94ce9fb468520275223c153574b00df6fe4bcc9 # v3
         with:
           registry: ${{ env.REGISTRY }}
           username: ${{ github.actor }}
@@ -29,7 +29,7 @@ jobs:
 
       - name: Extract metadata for Docker
         id: meta
-        uses: docker/metadata-action@v5
+        uses: docker/metadata-action@c299e40c65443455700f0fdfc63efafe5b349051 # v5
         with:
           images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
           tags: |
@@ -38,10 +38,10 @@ jobs:
             type=raw,value=latest,enable=${{ !contains(github.ref, '-alpha') && !contains(github.ref, '-beta') && !contains(github.ref, '-rc') }}
 
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v3
+        uses: docker/setup-buildx-action@8d2750c68a42422c14e847fe6c8ac0403b4cbd6f # v3
 
       - name: Build and push Docker image
-        uses: docker/build-push-action@v6
+        uses: docker/build-push-action@10e90e3645eae34f1e60eeb005ba3a3d33f178e8 # v6
         with:
           context: .
           push: true
diff --git a/Dockerfile b/Dockerfile
index cc6dc58..841cdd8 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,8 +1,8 @@
 # Stage 1: Builder
-FROM python:3.14-slim AS builder
+FROM python:3.14-slim@sha256:6a27522252aef8432841f224d9baaa6e9fce07b07584154fa0b9a96603af7456 AS builder
 
 # Install uv
-COPY --from=ghcr.io/astral-sh/uv:latest /uv /usr/local/bin/uv
+COPY --from=ghcr.io/astral-sh/uv:latest@sha256:edd1fd89f3e5b005814cc8f777610445d7b7e3ed05361f9ddfae67bebfe8456a /uv /usr/local/bin/uv
 
 WORKDIR /app
 
@@ -20,7 +20,7 @@ RUN uv sync --frozen --no-dev
 
 
 # Stage 2: Runtime
-FROM python:3.14-slim
+FROM python:3.14-slim@sha256:6a27522252aef8432841f224d9baaa6e9fce07b07584154fa0b9a96603af7456
 
 # Create non-root user
 RUN useradd --create-home --shell /bin/bash appuser
diff --git a/deploy/prod/docker-compose.yml b/deploy/prod/docker-compose.yml
index 3a0c805..3573485 100644
--- a/deploy/prod/docker-compose.yml
+++ b/deploy/prod/docker-compose.yml
@@ -1,7 +1,7 @@
 # Production environment
 services:
   grist-mcp:
-    image: ghcr.io/xe138/grist-mcp-server:latest
+    image: ghcr.io/xe138/grist-mcp-server:latest@sha256:2ef22bfac6cfbcbbfc513f61eaea3414b3a531d79e9d1d39bf6757cc9e27ea9a
     ports:
       - "${PORT:-3000}:3000"
     volumes:
diff --git a/tests/integration/mock_grist/Dockerfile b/tests/integration/mock_grist/Dockerfile
index 96017d9..8c680cd 100644
--- a/tests/integration/mock_grist/Dockerfile
+++ b/tests/integration/mock_grist/Dockerfile
@@ -1,4 +1,4 @@
-FROM python:3.14-slim
+FROM python:3.14-slim@sha256:6a27522252aef8432841f224d9baaa6e9fce07b07584154fa0b9a96603af7456
 
 WORKDIR /app