diff --git a/.github/ISSUE_TEMPLATE/2.server_bug_report.yml b/.github/ISSUE_TEMPLATE/2.server_bug_report.yml
index f5abb861e4..432f0f6440 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. v4.0.3)
+        - Ruby version: (from `ruby --version`, eg. v4.0.4)
         - 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 95efe3fd3c..e459581074 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. v4.0.3)
+        - Ruby version: (from `ruby --version`, eg. v4.0.4)
         - 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 75e87eb90f..aaf6dc752a 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@94e4d89d3e6c1c7599e0210d114c5ffb23f1a866 # v1
+      uses: ruby/setup-ruby@6aaa311d81eba98ae12eaffbcb63296ace0efcde # 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 0cbbeb5878..797dd5687e 100644
--- a/.github/workflows/bundler-audit.yml
+++ b/.github/workflows/bundler-audit.yml
@@ -31,7 +31,7 @@ jobs:
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
 
       - name: Set up Ruby
-        uses: ruby/setup-ruby@94e4d89d3e6c1c7599e0210d114c5ffb23f1a866 # v1
+        uses: ruby/setup-ruby@6aaa311d81eba98ae12eaffbcb63296ace0efcde # v1
         with:
           bundler-cache: true
 
diff --git a/.github/workflows/lint-haml.yml b/.github/workflows/lint-haml.yml
index b59a4b2d69..a453091c1a 100644
--- a/.github/workflows/lint-haml.yml
+++ b/.github/workflows/lint-haml.yml
@@ -36,7 +36,7 @@ jobs:
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
 
       - name: Set up Ruby
-        uses: ruby/setup-ruby@94e4d89d3e6c1c7599e0210d114c5ffb23f1a866 # v1
+        uses: ruby/setup-ruby@6aaa311d81eba98ae12eaffbcb63296ace0efcde # v1
         with:
           bundler-cache: true
 
diff --git a/.github/workflows/lint-ruby.yml b/.github/workflows/lint-ruby.yml
index ae4cc6faf2..942192faa1 100644
--- a/.github/workflows/lint-ruby.yml
+++ b/.github/workflows/lint-ruby.yml
@@ -38,7 +38,7 @@ jobs:
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
 
       - name: Set up Ruby
-        uses: ruby/setup-ruby@94e4d89d3e6c1c7599e0210d114c5ffb23f1a866 # v1
+        uses: ruby/setup-ruby@6aaa311d81eba98ae12eaffbcb63296ace0efcde # v1
         with:
           bundler-cache: true
 
diff --git a/.ruby-version b/.ruby-version
index c4e41f9459..c5106e6d13 100644
--- a/.ruby-version
+++ b/.ruby-version
@@ -1 +1 @@
-4.0.3
+4.0.4
diff --git a/Dockerfile b/Dockerfile
index 6159df35e4..feb5b34b80 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="4.0.3"
+ARG RUBY_VERSION="4.0.4"
 # # 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 7570bb7b77..8223f7216e 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -132,7 +132,7 @@ GEM
     binding_of_caller (2.0.0)
       debug_inspector (>= 1.2.0)
     blurhash (0.1.8)
-    bootsnap (1.24.1)
+    bootsnap (1.24.4)
       msgpack (~> 1.2)
     brakeman (8.0.4)
       racc
@@ -1097,7 +1097,7 @@ DEPENDENCIES
   xorcist (~> 1.1)
 
 RUBY VERSION
-  ruby 4.0.3
+  ruby 4.0.4
 
 BUNDLED WITH
   4.0.11