diff --git a/Gemfile b/Gemfile
index e299c383..1ce627ef 100755
--- a/Gemfile
+++ b/Gemfile
@@ -11,8 +11,8 @@ group :development, :test do
   # auto-load factories from spec/factories
   gem 'factory_bot_rails'
 
-  # Allow Rails 7.0 through 8.0 for upgrade compatibility
-  gem 'rails', '>= 7.0', '< 8.1'
+  # Allow Rails 7.0 through 8.1 for upgrade compatibility
+  gem 'rails', '>= 7.0', '< 9.0'
   gem 'net-smtp', require: false
 
   # Used to create fake data
diff --git a/metasploit_data_models.gemspec b/metasploit_data_models.gemspec
index 77c22bcc..c1a5e6bf 100644
--- a/metasploit_data_models.gemspec
+++ b/metasploit_data_models.gemspec
@@ -25,6 +25,8 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'yard-activerecord'
   # embed ERDs on index, namespace Module and Class<ApplicationRecord> pages
   s.add_development_dependency 'yard-metasploit-erd'
+  # required by rails-erd >= 2.1.0 (no longer a transitive dep)
+  s.add_development_dependency 'ruby-graphviz', '~> 1.2'
 
   s.add_development_dependency 'rake'
 
@@ -33,14 +35,12 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'pry'
 
 
-  # Rails 8.0 upgrade: widened from '~> 7.0' (which means >= 7.0, < 8.0) to
-  # '>= 7.0', '< 8.1' so this gem resolves with both Rails 7.x and 8.0.
-  # The old pessimistic constraint hard-blocked Bundler from pulling Rails 8.
-  s.add_runtime_dependency 'activerecord', '>= 7.0', '< 8.1'
-  s.add_runtime_dependency 'activesupport', '>= 7.0', '< 8.1'
+  # Rails 8.1 upgrade: cap raised to < 9.0 so this gem resolves with Rails 7.x, 8.0, and 8.1.
+  s.add_runtime_dependency 'activerecord', '>= 7.0', '< 9.0'
+  s.add_runtime_dependency 'activesupport', '>= 7.0', '< 9.0'
   s.add_runtime_dependency 'metasploit-concern'
   s.add_runtime_dependency 'metasploit-model', '>= 5.0.4'
-  s.add_runtime_dependency 'railties', '>= 7.0', '< 8.1'
+  s.add_runtime_dependency 'railties', '>= 7.0', '< 9.0'
   s.add_runtime_dependency 'webrick'
 
   # os fingerprinting