diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index d237619714c0ec2a39ae441c57f13edd85be5779..1c5d4e99c44613df85783744081b022688a3dc35 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -70,7 +70,7 @@ lint_python_scripts:
 
 .build_docker_image:
   extends: .docker_image_builder_job
-  image: docker:20.10.10
+  image: docker:20.10.21
   variables:
     BUILD_TARGET: ""
   before_script:
@@ -100,7 +100,7 @@ lint_python_scripts:
 
 build_docker_dind_image:
   stage: pre-build
-  image: docker:20.10.10
+  image: docker:20.10.21
   variables:
     DOCKER_BUILDKIT: 1
     DOCKER_DRIVER: overlay2
@@ -115,7 +115,7 @@ build_docker_dind_image:
       exists:
         - Dockerfile.docker-dind
   services:
-    - docker:20.10.10-dind
+    - docker:20.10.21-dind
   tags:
     - public-runner-docker
 
diff --git a/Dockerfile.docker-builder b/Dockerfile.docker-builder
index 9d1681f0c695792316e27df35c71b665f9818103..c28a018051d06fe1ab9bfb3dbeb98a64cf36aa07 100644
--- a/Dockerfile.docker-builder
+++ b/Dockerfile.docker-builder
@@ -1,4 +1,4 @@
-FROM docker:20.10.10 AS docker-builder
+FROM docker:20.10.21 AS docker-builder
 
 COPY scripts/bash/*.sh /usr/local/bin
 RUN apk add --no-cache bash git ca-certificates curl
\ No newline at end of file
diff --git a/Dockerfile.docker-dind b/Dockerfile.docker-dind
index 309b2d1d48a22d00e7e370b04d730e14ff9bd7c2..979f9ad7394363fe693f7d9bfdc1c1843846567d 100644
--- a/Dockerfile.docker-dind
+++ b/Dockerfile.docker-dind
@@ -1,7 +1,7 @@
 # To workaround a gitlab healthcheck bug, expose just single port. 
 # See https://gitlab.com/gitlab-org/gitlab-runner/-/issues/29130#note_1028331564 and
 # https://gitlab.com/search?search=Service+docker+dind+probably+didn%27t+start+properly&nav_source=navbar&project_id=250833&group_id=9970&scope=issues&sort=updated_desc
-FROM docker:20.10.10-dind as upstream
+FROM docker:20.10.21-dind as upstream
 
 FROM scratch
 
diff --git a/README.md b/README.md
index f096c0c54512cbf13e698b38df63ef137b24dfbd..b5c2ea2e294e6c59b33e23000a9a8b53f5dae815 100644
--- a/README.md
+++ b/README.md
@@ -26,7 +26,7 @@ The former is an XSL transformation file, which can be used to transform checkst
 The latter is a Compose file for setting up a simple Docker-in-Docker container. To connect to that container with a Docker CLI one use command like:
 
 ```bash
-docker run -it --rm --network docker -e DOCKER_TLS_CERTDIR=/certs -v docker-certs-client:/certs/client:ro --name docker-cli docker:20.10.10
+docker run -it --rm --network docker -e DOCKER_TLS_CERTDIR=/certs -v docker-certs-client:/certs/client:ro --name docker-cli docker:20.10.21
 ```
 
 The iportant bit is connecting to the right network (`--network docker`) and mounting the TLS certificates (`-e DOCKER_TLS_CERTDIR=/certs -v docker-certs-client:/certs/client:ro`). Other parameters can be changed to suit your purposes.
diff --git a/misc/docker-compose.dind.yml b/misc/docker-compose.dind.yml
index 3853e77c5d74cc502d30dd7454934d969f6bac73..f279729481fb26518646d9700c267c034355f694 100644
--- a/misc/docker-compose.dind.yml
+++ b/misc/docker-compose.dind.yml
@@ -1,7 +1,7 @@
 version: '3.9'
 services:
   docker:
-    image: docker:20.10.10-dind
+    image: docker:20.10.21-dind
     privileged: true
     environment:
       - DOCKER_TLS_CERTDIR=/certs