diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a99e0796f..f7e74b9b3 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -12,7 +12,7 @@ jobs:
       - name: Install Ruby
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: 4.0.5
+          ruby-version: 4.0.9
       - name: Cache gems
         uses: actions/cache@v4
         with:
@@ -37,7 +37,7 @@ jobs:
       - name: Install Ruby
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: 4.0.5
+          ruby-version: 4.0.9
       - name: Cache gems
         uses: actions/cache@v4
         with:
@@ -89,7 +89,7 @@ jobs:
       - name: Install Ruby
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: 4.0.5
+          ruby-version: 4.0.9
       - name: Cache gems
         uses: actions/cache@v4
         with:
@@ -113,7 +113,7 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 15
     container:
-      image: ruby:4.0.5-alpine
+      image: ruby:4.0.9-alpine
 
     services:
       postgres:
diff --git a/Dockerfile b/Dockerfile
index 8707624c9..afb53882b 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM ruby:4.0.5-alpine AS download
+FROM ruby:4.0.9-alpine AS download
 
 WORKDIR /fonts
 
@@ -17,7 +17,7 @@ RUN apk --no-cache add wget unzip && \
     mkdir -p /pdfium-linux && \
     unzip -q pdfium-linux.zip -d /pdfium-linux
 
-FROM ruby:4.0.5-alpine AS webpack
+FROM ruby:4.0.9-alpine AS webpack
 
 ENV RAILS_ENV=production
 ENV NODE_ENV=production
@@ -44,7 +44,7 @@ COPY ./app/views ./app/views
 
 RUN echo "gem 'shakapacker'" > Gemfile && ./bin/shakapacker
 
-FROM ruby:4.0.5-alpine AS app
+FROM ruby:4.0.9-alpine AS app
 
 ENV RAILS_ENV=production
 ENV BUNDLE_WITHOUT="development:test"
diff --git a/Gemfile b/Gemfile
index fc482901b..86f3c0856 100644
--- a/Gemfile
+++ b/Gemfile
@@ -2,7 +2,7 @@
 
 source 'https://rubygems.org'
 
-ruby '4.0.5'
+ruby '4.0.9'
 
 gem 'addressable'
 gem 'arabic-letter-connector', require: false
diff --git a/Gemfile.lock b/Gemfile.lock
index ee3d8e886..68e092c96 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -664,7 +664,7 @@ DEPENDENCIES
   xlsxtream
 
 RUBY VERSION
-  ruby 4.0.5
+  ruby 4.0.9
 
 BUNDLED WITH
   4.0.3