diff --git a/.github/ISSUE_TEMPLATE/2.server_bug_report.yml b/.github/ISSUE_TEMPLATE/2.server_bug_report.yml
index e5b809d6724..cbc7106c0a2 100644
--- a/.github/ISSUE_TEMPLATE/2.server_bug_report.yml
+++ b/.github/ISSUE_TEMPLATE/2.server_bug_report.yml
@@ -59,7 +59,7 @@ body:
         Any additional technical details you may have, like logs or error traces
       value: |
         If this is happening on your own Mastodon server, please fill out those:
-        - Ruby version: (from `ruby --version`, eg. v4.0.5)
+        - Ruby version: (from `ruby --version`, eg. v4.0.6)
         - Node.js version: (from `node --version`, eg. v22.16.0)
     validations:
       required: false
diff --git a/.github/ISSUE_TEMPLATE/3.troubleshooting.yml b/.github/ISSUE_TEMPLATE/3.troubleshooting.yml
index 529a42204b1..c3e6f35a767 100644
--- a/.github/ISSUE_TEMPLATE/3.troubleshooting.yml
+++ b/.github/ISSUE_TEMPLATE/3.troubleshooting.yml
@@ -61,7 +61,7 @@ body:
       value: |
         Please at least include those informations:
         - Operating system: (eg. Ubuntu 24.04.2)
-        - Ruby version: (from `ruby --version`, eg. v4.0.5)
+        - Ruby version: (from `ruby --version`, eg. v4.0.6)
         - Node.js version: (from `node --version`, eg. v22.16.0)
     validations:
       required: false
diff --git a/.github/actions/setup-ruby/action.yml b/.github/actions/setup-ruby/action.yml
index 3c8317ad5bf..64b7c25145c 100644
--- a/.github/actions/setup-ruby/action.yml
+++ b/.github/actions/setup-ruby/action.yml
@@ -23,7 +23,7 @@ runs:
           ${{ inputs.additional-system-dependencies }}
 
     - name: Set up Ruby
-      uses: ruby/setup-ruby@d45b1a4e94b71acab930e56e79c6aa188764e7f9 # v1
+      uses: ruby/setup-ruby@6e5d382445ae5590b7449d8b3bc8cb1c2c27f617 # v1
       with:
         ruby-version: ${{ inputs.ruby-version }}
         bundler-cache: true
diff --git a/.github/workflows/bundler-audit.yml b/.github/workflows/bundler-audit.yml
index fb5c256214c..994496eadd9 100644
--- a/.github/workflows/bundler-audit.yml
+++ b/.github/workflows/bundler-audit.yml
@@ -32,7 +32,7 @@ jobs:
         uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6
 
       - name: Set up Ruby
-        uses: ruby/setup-ruby@d45b1a4e94b71acab930e56e79c6aa188764e7f9 # v1
+        uses: ruby/setup-ruby@6e5d382445ae5590b7449d8b3bc8cb1c2c27f617 # v1
         with:
           bundler-cache: true
 
diff --git a/.github/workflows/lint-haml.yml b/.github/workflows/lint-haml.yml
index 2bfdc897718..c3415937cb3 100644
--- a/.github/workflows/lint-haml.yml
+++ b/.github/workflows/lint-haml.yml
@@ -35,7 +35,7 @@ jobs:
         uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6
 
       - name: Set up Ruby
-        uses: ruby/setup-ruby@d45b1a4e94b71acab930e56e79c6aa188764e7f9 # v1
+        uses: ruby/setup-ruby@6e5d382445ae5590b7449d8b3bc8cb1c2c27f617 # v1
         with:
           bundler-cache: true
 
diff --git a/.github/workflows/lint-ruby.yml b/.github/workflows/lint-ruby.yml
index df2eedfafab..f796f47bf6a 100644
--- a/.github/workflows/lint-ruby.yml
+++ b/.github/workflows/lint-ruby.yml
@@ -37,7 +37,7 @@ jobs:
         uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6
 
       - name: Set up Ruby
-        uses: ruby/setup-ruby@d45b1a4e94b71acab930e56e79c6aa188764e7f9 # v1
+        uses: ruby/setup-ruby@6e5d382445ae5590b7449d8b3bc8cb1c2c27f617 # v1
         with:
           bundler-cache: true
 
diff --git a/.ruby-version b/.ruby-version
index 7636e75650d..d13e837c8ec 100644
--- a/.ruby-version
+++ b/.ruby-version
@@ -1 +1 @@
-4.0.5
+4.0.6
diff --git a/Dockerfile b/Dockerfile
index 57669d21161..350f1ddc39d 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -13,7 +13,7 @@ ARG BASE_REGISTRY="docker.io"
 
 # Ruby image to use for base image, change with [--build-arg RUBY_VERSION="4.0.x"]
 # renovate: datasource=docker depName=docker.io/ruby
-ARG RUBY_VERSION="4.0.5"
+ARG RUBY_VERSION="4.0.6"
 # # Node.js version to use in base image, change with [--build-arg NODE_MAJOR_VERSION="22"]
 # renovate: datasource=node-version depName=node
 ARG NODE_MAJOR_VERSION="24"
diff --git a/Gemfile.lock b/Gemfile.lock
index d94ca199827..04729c9b449 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1097,7 +1097,7 @@ DEPENDENCIES
   xorcist (~> 1.1)
 
 RUBY VERSION
-  ruby 4.0.5
+  ruby 4.0.6
 
 BUNDLED WITH
   4.0.13