diff --git a/Gemfile b/Gemfile
index 4a642b3b4bf..0bd50ce9ffe 100644
--- a/Gemfile
+++ b/Gemfile
@@ -138,9 +138,6 @@ gem "rack-protection", "~> 3.2.0"
 # https://github.com/kickstarter/rack-attack
 gem "rack-attack", "~> 6.7.0"
 
-# CSP headers
-gem "secure_headers", "~> 7.1.0"
-
 # Browser detection for incompatibility checks
 gem "browser", "~> 6.2.0"
 
diff --git a/Gemfile.lock b/Gemfile.lock
index ce65a0fc6fc..c14ea7025d6 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1167,7 +1167,6 @@ GEM
       nokogiri (>= 1.16.8)
     scimitar (2.11.0)
       rails (>= 7.0)
-    secure_headers (7.1.0)
     securerandom (0.4.1)
     selenium-devtools (0.138.0)
       selenium-webdriver (~> 4.2)
@@ -1515,7 +1514,6 @@ DEPENDENCIES
   rubytree (~> 2.1.0)
   sanitize (~> 7.0.0)
   scimitar (~> 2.11)
-  secure_headers (~> 7.1.0)
   selenium-devtools
   selenium-webdriver (~> 4.20)
   semantic (~> 1.6.1)
@@ -1948,7 +1946,6 @@ CHECKSUMS
   safety_net_attestation (0.4.0) sha256=96be2d74e7ed26453a51894913449bea0e072f44490021545ac2d1c38b0718ce
   sanitize (7.0.0) sha256=269d1b9d7326e69307723af5643ec032ff86ad616e72a3b36d301ac75a273984
   scimitar (2.11.0) sha256=77cf779a843be7d572046acdcf0a1829bd3b1c33db993fa83faf7f1863d8c625
-  secure_headers (7.1.0) sha256=6b1f9d5f9507af2948f4636452c41c09371927836396c2185438ffdf0a731124
   securerandom (0.4.1) sha256=cc5193d414a4341b6e225f0cb4446aceca8e50d5e1888743fac16987638ea0b1
   selenium-devtools (0.138.0) sha256=596c08e114342dd89513bc3d18bbb2ae39e532864dbc25c09a48fb9922fc5b7b
   selenium-webdriver (4.34.0) sha256=ec7bb718cbe66fe2b247d8ca5e6ba26caed0976d76579d7cb2fadd8dae8b271e
diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
index c5e84856c4c..8ddad78f7ee 100644
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -56,6 +56,7 @@ class ApplicationController < ActionController::Base
   include OpenProjectErrorHelper
   include Security::DefaultUrlOptions
   include OpModalFlashable
+  include DynamicContentSecurityPolicy
 
   layout "base"
 
diff --git a/lib/open_project/patches/secure_headers_turbo_aware_nonce.rb b/app/controllers/concerns/dynamic_content_security_policy.rb
similarity index 63%
rename from lib/open_project/patches/secure_headers_turbo_aware_nonce.rb
rename to app/controllers/concerns/dynamic_content_security_policy.rb
index 64571d7bcd8..4d9e015a0c9 100644
--- a/lib/open_project/patches/secure_headers_turbo_aware_nonce.rb
+++ b/app/controllers/concerns/dynamic_content_security_policy.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 #-- copyright
 # OpenProject is an open source project management software.
 # Copyright (C) the OpenProject GmbH
@@ -25,18 +27,23 @@
 #
 # See COPYRIGHT and LICENSE files for more details.
 #++
-#
 
-module OpenProject::Patches::SecureHeadersTurboAwareNonce
-  def content_security_policy_script_nonce(request)
-    if request.env["HTTP_TURBO_REFERRER"].present?
-      request.env[SecureHeaders::NONCE_KEY] ||= request.env["HTTP_X_TURBO_NONCE"]
+module DynamicContentSecurityPolicy
+  ##
+  # Dynamically append sources to CSP directives
+  # This replaces the secure_headers named append functionality
+  def append_content_security_policy_directives(directives)
+    current_policy = current_content_security_policy
+    directives.each do |directive, source_values|
+      current_value = current_policy.send(directive) || current_policy.default_src
+      new_values =
+        if current_value == %w('none') # rubocop:disable Lint/PercentStringArray
+          source_values.compact.uniq
+        else
+          (current_value + source_values).compact.uniq
+        end
+
+      request.content_security_policy.send(directive, *new_values)
     end
-
-    super
   end
 end
-
-OpenProject::Patches.patch_gem_version "secure_headers", "7.1.0" do
-  SecureHeaders.singleton_class.prepend OpenProject::Patches::SecureHeadersTurboAwareNonce
-end
diff --git a/app/helpers/application_helper.rb b/app/helpers/application_helper.rb
index 38f86560e68..88dc6c9fb0e 100644
--- a/app/helpers/application_helper.rb
+++ b/app/helpers/application_helper.rb
@@ -219,6 +219,12 @@ module ApplicationHelper
     end
   end
 
+  # Backward compatibility helper for secure_headers gem migration
+  # Rails built-in CSP equivalent of nonced_javascript_tag
+  def nonced_javascript_tag(**, &)
+    javascript_tag(nonce: true, **, &)
+  end
+
   def to_path_param(path)
     path.to_s
   end
diff --git a/app/helpers/frontend_asset_helper.rb b/app/helpers/frontend_asset_helper.rb
index 38772224edd..b873ed0ea3a 100644
--- a/app/helpers/frontend_asset_helper.rb
+++ b/app/helpers/frontend_asset_helper.rb
@@ -66,7 +66,7 @@ module FrontendAssetHelper
   end
 
   def nonced_javascript_include_tag(path, **)
-    javascript_include_tag(path, nonce: content_security_policy_script_nonce, **)
+    javascript_include_tag(path, nonce: content_security_policy_nonce, **)
   end
 
   private
diff --git a/app/helpers/secure_headers_helper.rb b/app/helpers/secure_headers_helper.rb
index cebd0d6b9f2..826ce6626b8 100644
--- a/app/helpers/secure_headers_helper.rb
+++ b/app/helpers/secure_headers_helper.rb
@@ -29,10 +29,8 @@
 module SecureHeadersHelper
   ##
   # Output a rails +csp_meta_tag+ compatible tag
-  # while we're still using the +secure_headers+ gem.
+  # using Rails built-in CSP functionality.
   def secure_header_csp_meta_tag
-    tag :meta,
-        name: "csp-nonce",
-        content: content_security_policy_script_nonce
+    csp_meta_tag
   end
 end
diff --git a/app/views/layouts/_common_head.html.erb b/app/views/layouts/_common_head.html.erb
index 57d37e7add5..ce5f79f98d1 100644
--- a/app/views/layouts/_common_head.html.erb
+++ b/app/views/layouts/_common_head.html.erb
@@ -31,7 +31,7 @@
 <%= render "common/favicons" %>
 
 <%# Allow gon output when necessary %>
-<%= include_gon(nonce: content_security_policy_script_nonce) %>
+<%= include_gon(nonce: content_security_policy_nonce) %>
 
 <%# Include CLI assets (development) or prod build assets %>
 <%= include_frontend_assets %>
diff --git a/config/application.rb b/config/application.rb
index 8dfadd67d4d..67611fcb0ec 100644
--- a/config/application.rb
+++ b/config/application.rb
@@ -125,9 +125,6 @@ module OpenProject
     # http://stackoverflow.com/questions/4590229
     config.middleware.use Rack::TempfileReaper
 
-    # Move secure_headers middleware to after the ShowExceptions
-    config.middleware.move_after ActionDispatch::ShowExceptions, SecureHeaders::Middleware
-
     # Add lookbook preview paths when enabled
     if OpenProject::Configuration.lookbook_enabled?
       config.paths.add Primer::ViewComponents::Engine.root.join("app/components").to_s, eager_load: true
diff --git a/config/initializers/content_security_policy.rb b/config/initializers/content_security_policy.rb
index b3076b38fe1..e3b844bc760 100644
--- a/config/initializers/content_security_policy.rb
+++ b/config/initializers/content_security_policy.rb
@@ -1,25 +1,100 @@
+# frozen_string_literal: true
+
 # Be sure to restart your server when you modify this file.
 
 # Define an application-wide content security policy.
 # See the Securing Rails Applications Guide for more information:
 # https://guides.rubyonrails.org/security.html#content-security-policy-header
 
-# Rails.application.configure do
-#   config.content_security_policy do |policy|
-#     policy.default_src :self, :https
-#     policy.font_src    :self, :https, :data
-#     policy.img_src     :self, :https, :data
-#     policy.object_src  :none
-#     policy.script_src  :self, :https
-#     policy.style_src   :self, :https
-#     # Specify URI for violation reports
-#     # policy.report_uri "/csp-violation-report-endpoint"
-#   end
-#
-#   # Generate session nonces for permitted importmap, inline scripts, and inline styles.
-#   config.content_security_policy_nonce_generator = ->(request) { request.session.id.to_s }
-#   config.content_security_policy_nonce_directives = %w(script-src style-src)
-#
-#   # Report violations without enforcing the policy.
-#   # config.content_security_policy_report_only = true
-# end
+Rails.application.config.after_initialize do
+  Rails.application.configure do
+    config.content_security_policy do |policy|
+      # Valid for assets
+      assets_src = ["'self'"]
+      asset_host = OpenProject::Configuration.rails_asset_host
+      assets_src << asset_host if asset_host.present?
+
+      # Valid for iframes
+      frame_src = %w['self' https://player.vimeo.com https://www.youtube.com] # rubocop:disable Lint/PercentStringArray
+      frame_src << OpenProject::Configuration[:security_badge_url]
+
+      # Default src
+      default_src = %w('self') # rubocop:disable Lint/PercentStringArray
+
+      # Attachment uploaders
+      default_src += OpenProject::Configuration.remote_storage_hosts
+
+      # Chargebee self-service
+      frame_src += [
+        "https://js.chargebee.com/",
+        "#{OpenProject::Configuration.enterprise_chargebee_site}.chargebee.com"
+      ]
+
+      default_src << "#{OpenProject::Configuration.enterprise_chargebee_site}.chargebee.com"
+
+      # Allow requests to CLI in dev mode
+      connect_src = default_src + [OpenProject::Configuration.enterprise_trial_creation_host]
+
+      # Rules for media (e.g. video sources)
+      media_src = default_src
+      media_src << asset_host if asset_host.present?
+
+      if OpenProject::Configuration.appsignal_frontend_key
+        connect_src += ["https://appsignal-endpoint.net"]
+      end
+
+      # Add proxy configuration for Angular CLI to csp
+      if FrontendAssetHelper.assets_proxied?
+        proxied = ["ws://#{Setting.host_name}", "http://#{Setting.host_name}",
+                   FrontendAssetHelper.cli_proxy.sub("http", "ws"), FrontendAssetHelper.cli_proxy]
+        connect_src += proxied
+        assets_src += proxied
+        media_src += proxied
+      end
+
+      # Allow to extend the script-src in specific situations
+      script_src = assets_src + %w(js.chargebee.com)
+
+      # Allow unsafe-eval for rack-mini-profiler
+      if Rails.env.development? && ENV.fetch("OPENPROJECT_RACK_PROFILER_ENABLED", false)
+        script_src += %w('unsafe-eval') # rubocop:disable Lint/PercentStringArray
+      end
+
+      # Allow ANDI bookmarklet to run in development mode
+      # https://www.ssa.gov/accessibility/andi/help/install.html
+      if Rails.env.development?
+        script_src += ["https://www.ssa.gov"]
+        assets_src += ["https://www.ssa.gov"]
+      end
+
+      # Configure CSP directives
+      policy.default_src(*default_src)
+      policy.base_uri("'self'")
+      policy.font_src(*assets_src, "data:", "'self'")
+      policy.form_action(*default_src)
+      policy.frame_src(*frame_src, "'self'")
+      policy.frame_ancestors("'self'")
+      policy.img_src("*", "data:", "blob:")
+      policy.script_src(*script_src)
+      policy.script_src_attr("'none'")
+      policy.style_src(*assets_src, "'unsafe-inline'")
+      policy.object_src(OpenProject::Configuration[:security_badge_url])
+      policy.connect_src(*connect_src)
+      policy.media_src(*media_src)
+    end
+
+    # Generate session nonces for permitted importmap, inline scripts, and inline styles.
+    # This handles Turbo integration natively
+    config.content_security_policy_nonce_generator = lambda do |request|
+      # Use Turbo nonce if available (for Turbo navigation)
+      if request.env["HTTP_TURBO_REFERRER"].present? && request.env["HTTP_X_TURBO_NONCE"].present?
+        request.env["HTTP_X_TURBO_NONCE"]
+      else
+        # Generate a new nonce based on session
+        SecureRandom.base64(16)
+      end
+    end
+
+    config.content_security_policy_nonce_directives = %w(script-src)
+  end
+end
diff --git a/config/initializers/lookbook.rb b/config/initializers/lookbook.rb
index eb74d34c9aa..d6d167b170b 100644
--- a/config/initializers/lookbook.rb
+++ b/config/initializers/lookbook.rb
@@ -22,49 +22,4 @@ Rails.application.configure do
   # Show notes first, all other panels next
   config.lookbook.preview_inspector.drawer_panels = [:notes, "*"]
   config.lookbook.ui_theme = "blue"
-
-  SecureHeaders::Configuration.named_append(:lookbook) do
-    proxied =
-      if FrontendAssetHelper.assets_proxied?
-        ["ws://#{Setting.host_name}", "http://#{Setting.host_name}",
-         FrontendAssetHelper.cli_proxy.sub("http", "ws"), FrontendAssetHelper.cli_proxy]
-      else
-        []
-      end
-
-    {
-      script_src: proxied + %w('unsafe-eval' 'unsafe-inline' 'self'), # rubocop:disable Lint/PercentStringArray
-      script_src_elem: proxied + %w('unsafe-eval' 'unsafe-inline' 'self'), # rubocop:disable Lint/PercentStringArray
-      style_src: proxied + %w('self' 'unsafe-inline'), # rubocop:disable Lint/PercentStringArray
-      style_src_attr: proxied + %w('self' 'unsafe-inline') # rubocop:disable Lint/PercentStringArray
-    }
-  end
-
-  # rubocop:disable Lint/ConstantDefinitionInBlock
-  module LookbookCspExtender
-    extend ActiveSupport::Concern
-
-    included do
-      before_action do
-        use_content_security_policy_named_append :lookbook
-      end
-    end
-  end
-  # rubocop:enable Lint/ConstantDefinitionInBlock
-
-  Rails.application.reloader.to_prepare do
-    Lookbook.add_input_type(:octicon, "lookbook/previews/inputs/octicon")
-
-    [
-      Lookbook::ApplicationController,
-      Lookbook::PreviewController,
-      Lookbook::PreviewsController,
-      Lookbook::PageController,
-      Lookbook::PagesController,
-      Lookbook::InspectorController,
-      Lookbook::EmbedsController
-    ].each do |controller|
-      controller.include LookbookCspExtender
-    end
-  end
 end
diff --git a/config/initializers/secure_headers.rb b/config/initializers/secure_headers.rb
deleted file mode 100644
index 6e0d364215f..00000000000
--- a/config/initializers/secure_headers.rb
+++ /dev/null
@@ -1,141 +0,0 @@
-# frozen_string_literal: true
-
-#-- copyright
-# OpenProject is an open source project management software.
-# Copyright (C) the OpenProject GmbH
-#
-# This program is free software; you can redistribute it and/or
-# modify it under the terms of the GNU General Public License version 3.
-#
-# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
-# Copyright (C) 2006-2013 Jean-Philippe Lang
-# Copyright (C) 2010-2013 the ChiliProject Team
-#
-# This program is free software; you can redistribute it and/or
-# modify it under the terms of the GNU General Public License
-# as published by the Free Software Foundation; either version 2
-# of the License, or (at your option) any later version.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with this program; if not, write to the Free Software
-# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
-#
-# See COPYRIGHT and LICENSE files for more details.
-#++
-
-# rubocop:disable Lint/PercentStringArray
-Rails.application.config.after_initialize do
-  SecureHeaders::Configuration.default do |config|
-    config.cookies = {
-      secure: true,
-      httponly: true
-    }
-
-    # Let Rails ActionDispatch::SSL middleware handle the Strict-Transport-Security header
-    config.hsts = SecureHeaders::OPT_OUT
-
-    config.x_frame_options = "SAMEORIGIN"
-    config.x_content_type_options = "nosniff"
-    config.x_xss_protection = "1; mode=block"
-    config.x_permitted_cross_domain_policies = "none"
-    config.referrer_policy = "origin-when-cross-origin"
-
-    # Valid for assets
-    assets_src = ["'self'"]
-    asset_host = OpenProject::Configuration.rails_asset_host
-    assets_src << asset_host if asset_host.present?
-
-    # Valid for iframes
-    frame_src = %w['self' https://player.vimeo.com https://www.youtube.com]
-    frame_src << OpenProject::Configuration[:security_badge_url]
-
-    # Default src
-    default_src = %w('self')
-
-    # Attachment uploaders
-    default_src += OpenProject::Configuration.remote_storage_hosts
-
-    # Chargebee self-service
-    frame_src += [
-      "https://js.chargebee.com/",
-      "#{OpenProject::Configuration.enterprise_chargebee_site}.chargebee.com"
-    ]
-
-    default_src << "#{OpenProject::Configuration.enterprise_chargebee_site}.chargebee.com"
-
-    # Allow requests to CLI in dev mode
-    connect_src = default_src + [OpenProject::Configuration.enterprise_trial_creation_host]
-
-    # Rules for media (e.g. video sources)
-    media_src = default_src
-    media_src << asset_host if asset_host.present?
-
-    if OpenProject::Configuration.appsignal_frontend_key
-      connect_src += ["https://appsignal-endpoint.net"]
-    end
-
-    # Add proxy configuration for Angular CLI to csp
-    if FrontendAssetHelper.assets_proxied?
-      proxied = ["ws://#{Setting.host_name}", "http://#{Setting.host_name}",
-                 FrontendAssetHelper.cli_proxy.sub("http", "ws"), FrontendAssetHelper.cli_proxy]
-      connect_src += proxied
-      assets_src += proxied
-      media_src += proxied
-    end
-
-    # Allow to extend the script-src in specific situations
-    script_src = assets_src + %w(js.chargebee.com)
-
-    # Allow unsafe-eval for rack-mini-profiler
-    if Rails.env.development? && ENV.fetch("OPENPROJECT_RACK_PROFILER_ENABLED", false)
-      script_src += %w('unsafe-eval')
-    end
-
-    # Allow ANDI bookmarklet to run in development mode
-    # https://www.ssa.gov/accessibility/andi/help/install.html
-    if Rails.env.development?
-      script_src += ["https://www.ssa.gov"]
-      assets_src += ["https://www.ssa.gov"]
-    end
-
-    config.csp = {
-      preserve_schemes: true,
-      # Don't append unsafe-inline in CSP as a fallback
-      disable_nonce_backwards_compatibility: true,
-
-      # Fallback when no value is defined
-      default_src:,
-      # Allowed uri in <base> tag
-      base_uri: %w('self'),
-
-      # Allow fonts from self, asset host, or DATA uri
-      font_src: assets_src + %w(data: 'self'),
-      # Form targets can only be self
-      form_action: default_src,
-      # Allow iframe from vimeo (welcome video)
-      frame_src: frame_src + %w('self'),
-      frame_ancestors: %w('self'),
-      # Allow images from anywhere including data urls and blobs (used in resizing)
-      img_src: %w(* data: blob:),
-      # Allow scripts from self
-      script_src:,
-      script_src_attr: %w('none'),
-      # Allow unsafe-inline styles
-      style_src: assets_src + %w('unsafe-inline'),
-      # Allow object-src from Release API
-      object_src: [OpenProject::Configuration[:security_badge_url]],
-
-      # Connect sources for CLI in dev mode
-      connect_src:,
-
-      # Allow videos from self and from the asset proxy in dev mode.
-      media_src:
-    }
-  end
-end
-# rubocop:enable Lint/PercentStringArray
diff --git a/modules/recaptcha/app/controllers/recaptcha/request_controller.rb b/modules/recaptcha/app/controllers/recaptcha/request_controller.rb
index 320d60a2893..f8385b7a42b 100644
--- a/modules/recaptcha/app/controllers/recaptcha/request_controller.rb
+++ b/modules/recaptcha/app/controllers/recaptcha/request_controller.rb
@@ -30,11 +30,11 @@ module ::Recaptcha
     # Request verification form
     def perform
       if OpenProject::Recaptcha::Configuration.use_hcaptcha?
-        use_content_security_policy_named_append(:hcaptcha)
+        allow_captcha_service(:hcaptcha)
       elsif OpenProject::Recaptcha::Configuration.use_turnstile?
-        use_content_security_policy_named_append(:turnstile)
+        allow_captcha_service(:turnstile)
       elsif OpenProject::Recaptcha::Configuration.use_recaptcha?
-        use_content_security_policy_named_append(:recaptcha)
+        allow_captcha_service(:recaptcha)
       end
     end
 
@@ -163,5 +163,31 @@ module ::Recaptcha
     def failure_stage_redirect
       redirect_to authentication_stage_failure_path :recaptcha
     end
+
+    ##
+    # Add CAPTCHA service CSP rules
+    def allow_captcha_service(service_type)
+      case service_type.to_sym
+      when :recaptcha
+        append_content_security_policy_directives(
+          frame_src: %w[https://www.recaptcha.net/recaptcha/ https://www.gstatic.com/recaptcha/]
+        )
+      when :hcaptcha
+        sources = %w[https://*.hcaptcha.com]
+        append_content_security_policy_directives(
+          frame_src: sources,
+          script_src: sources,
+          style_src: sources,
+          connect_src: sources
+        )
+      when :turnstile
+        sources = %w[https://challenges.cloudflare.com]
+        append_content_security_policy_directives(
+          frame_src: sources,
+          style_src: sources,
+          connect_src: sources
+        )
+      end
+    end
   end
 end
diff --git a/modules/recaptcha/app/views/recaptcha/request/perform.html.erb b/modules/recaptcha/app/views/recaptcha/request/perform.html.erb
index 8e7cf27be13..b2b970ccca0 100644
--- a/modules/recaptcha/app/views/recaptcha/request/perform.html.erb
+++ b/modules/recaptcha/app/views/recaptcha/request/perform.html.erb
@@ -6,7 +6,7 @@
       <% input_name = "g-recaptcha-response" %>
       <input type="hidden" name="<%= input_name %>">
       <%= recaptcha_tags(
-            nonce: content_security_policy_script_nonce,
+            nonce: content_security_policy_nonce,
             callback: "submitRecaptchaForm",
             site_key: recaptcha_settings["website_key"]
           ) %>
@@ -29,7 +29,7 @@
       <% end %>
     <% elsif recaptcha_settings['recaptcha_type'] == ::OpenProject::Recaptcha::TYPE_V3 %>
       <%= recaptcha_v3 action: "login",
-                       nonce: content_security_policy_script_nonce,
+                       nonce: content_security_policy_nonce,
                        callback: "submitRecaptchaForm",
                        site_key: recaptcha_settings["website_key"] %>
 
diff --git a/modules/recaptcha/lib/open_project/recaptcha/engine.rb b/modules/recaptcha/lib/open_project/recaptcha/engine.rb
index 023a9ba73b1..94a826e2a29 100644
--- a/modules/recaptcha/lib/open_project/recaptcha/engine.rb
+++ b/modules/recaptcha/lib/open_project/recaptcha/engine.rb
@@ -28,26 +28,6 @@ module OpenProject::Recaptcha
     end
 
     config.after_initialize do
-      SecureHeaders::Configuration.named_append(:recaptcha) do
-        {
-          frame_src: %w[https://www.recaptcha.net/recaptcha/ https://www.gstatic.com/recaptcha/]
-        }
-      end
-
-      SecureHeaders::Configuration.named_append(:hcaptcha) do
-        value = %w(https://*.hcaptcha.com)
-        keys = %i(frame_src script_src style_src connect_src)
-
-        keys.index_with value
-      end
-
-      SecureHeaders::Configuration.named_append(:turnstile) do
-        value = %w(https://challenges.cloudflare.com)
-        keys = %i(frame_src style_src connect_src)
-
-        keys.index_with value
-      end
-
       OpenProject::Authentication::Stage.register(
         :recaptcha,
         nil,
diff --git a/spec/support/shared/with_direct_uploads.rb b/spec/support/shared/with_direct_uploads.rb
index 523d80cc6b7..c82a1288070 100644
--- a/spec/support/shared/with_direct_uploads.rb
+++ b/spec/support/shared/with_direct_uploads.rb
@@ -65,19 +65,23 @@ class WithDirectUploads
   def around(example)
     example.metadata[:javascript_driver] = example.metadata[:driver] = :chrome_billy
 
-    csp_config = SecureHeaders::Configuration.instance_variable_get(:@default_config).csp
+    # Temporarily modify CSP for direct uploads testing
+    original_csp = Rails.application.config.content_security_policy
 
-    connect_src = csp_config[:connect_src].dup
-    form_action = csp_config[:form_action].dup
+    Rails.application.config.content_security_policy do |policy|
+      # Copy existing policy and add test bucket domain
+      original_csp.call(policy) if original_csp
+
+      # Add test bucket to connect_src and form_action for direct uploads
+      policy.connect_src(*(policy.instance_variable_get(:@directives)[:connect_src] || []), "test-bucket.s3.amazonaws.com")
+      policy.form_action(*(policy.instance_variable_get(:@directives)[:form_action] || []), "test-bucket.s3.amazonaws.com")
+    end
 
     begin
-      csp_config[:connect_src] << "test-bucket.s3.amazonaws.com"
-      csp_config[:form_action] << "test-bucket.s3.amazonaws.com"
-
       example.run
     ensure
-      csp_config[:connect_src] = connect_src
-      csp_config[:form_action] = form_action
+      # Restore original CSP configuration
+      Rails.application.config.content_security_policy = original_csp
     end
   end