diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
index 3322bce2bf..9d5f4d0a2d 100644
--- a/.rubocop_todo.yml
+++ b/.rubocop_todo.yml
@@ -21,11 +21,11 @@ Metrics/BlockNesting:
 
 # Configuration parameters: AllowedMethods, AllowedPatterns.
 Metrics/CyclomaticComplexity:
-  Max: 25
+  Enabled: false
 
 # Configuration parameters: AllowedMethods, AllowedPatterns.
 Metrics/PerceivedComplexity:
-  Max: 27
+  Enabled: false
 
 Rails/OutputSafety:
   Exclude:
diff --git a/SECURITY.md b/SECURITY.md
index 385c946512..bd8f5ab25d 100644
--- a/SECURITY.md
+++ b/SECURITY.md
@@ -17,5 +17,4 @@ A "vulnerability in Mastodon" is a vulnerability in the code distributed through
 | ------- | ---------------- |
 | 4.4.x   | Yes              |
 | 4.3.x   | Until 2026-05-06 |
-| 4.2.x   | Until 2026-01-08 |
-| < 4.2   | No               |
+| < 4.3   | No               |
diff --git a/app/controllers/concerns/cache_concern.rb b/app/controllers/concerns/cache_concern.rb
index 1823b5b8ed..d43bdd904e 100644
--- a/app/controllers/concerns/cache_concern.rb
+++ b/app/controllers/concerns/cache_concern.rb
@@ -19,7 +19,7 @@ module CacheConcern
   # from being used as cache keys, while allowing to `Vary` on them (to not serve
   # anonymous cached data to authenticated requests when authentication matters)
   def enforce_cache_control!
-    vary = response.headers['Vary']&.split&.map { |x| x.strip.downcase }
+    vary = response.headers['Vary'].to_s.split(',').map { |x| x.strip.downcase }.reject(&:empty?)
     return unless vary.present? && %w(cookie authorization signature).any? { |header| vary.include?(header) && request.headers[header].present? }
 
     response.cache_control.replace(private: true, no_store: true)
diff --git a/app/lib/activitypub/activity.rb b/app/lib/activitypub/activity.rb
index 322f3e27ad..f5b55fff6a 100644
--- a/app/lib/activitypub/activity.rb
+++ b/app/lib/activitypub/activity.rb
@@ -22,13 +22,13 @@ class ActivityPub::Activity
   class << self
     def factory(json, account, **options)
       @json = json
-      klass&.new(json, account, **options)
+      klass_for(json)&.new(json, account, **options)
     end
 
     private
 
-    def klass
-      case @json['type']
+    def klass_for(json)
+      case json['type']
       when 'Create'
         ActivityPub::Activity::Create
       when 'Announce'
diff --git a/app/lib/connection_pool/shared_connection_pool.rb b/app/lib/connection_pool/shared_connection_pool.rb
index 1cfcc5823b..c7dd747eda 100644
--- a/app/lib/connection_pool/shared_connection_pool.rb
+++ b/app/lib/connection_pool/shared_connection_pool.rb
@@ -41,12 +41,17 @@ class ConnectionPool::SharedConnectionPool < ConnectionPool
       # ConnectionPool 2.4+ calls `checkin(force: true)` after fork.
       # When this happens, we should remove all connections from Thread.current
 
-      ::Thread.current.keys.each do |name| # rubocop:disable Style/HashEachMethods
-        next unless name.to_s.start_with?("#{@key}-")
+      connection_keys = ::Thread.current.keys.select { |key| key.to_s.start_with?("#{@key}-") && !key.to_s.start_with?("#{@key_count}-") }
+      count_keys = ::Thread.current.keys.select { |key| key.to_s.start_with?("#{@key_count}-") }
 
-        @available.push(::Thread.current[name])
-        ::Thread.current[name] = nil
+      connection_keys.each do |key|
+        @available.push(::Thread.current[key])
+        ::Thread.current[key] = nil
       end
+      count_keys.each do |key|
+        ::Thread.current[key] = nil
+      end
+
     elsif ::Thread.current[key(preferred_tag)]
       if ::Thread.current[key_count(preferred_tag)] == 1
         @available.push(::Thread.current[key(preferred_tag)])
diff --git a/app/lib/feed_manager.rb b/app/lib/feed_manager.rb
index 9332aea2df..8473d348d7 100644
--- a/app/lib/feed_manager.rb
+++ b/app/lib/feed_manager.rb
@@ -491,6 +491,7 @@ class FeedManager
     return :filter    if status.reply? && (status.in_reply_to_id.nil? || status.in_reply_to_account_id.nil?)
     return :skip_home if timeline_type != :list && crutches[:exclusive_list_users][status.account_id].present?
     return :filter    if crutches[:languages][status.account_id].present? && status.language.present? && !crutches[:languages][status.account_id].include?(status.language)
+    return :filter    if status.reblog? && status.reblog.blank?
 
     check_for_blocks = crutches[:active_mentions][status.id] || []
     check_for_blocks.push(status.account_id)
diff --git a/app/lib/signature_parser.rb b/app/lib/signature_parser.rb
index 7a75080d98..00a45b8251 100644
--- a/app/lib/signature_parser.rb
+++ b/app/lib/signature_parser.rb
@@ -25,9 +25,13 @@ class SignatureParser
 
     # Use `skip` instead of `scan` as we only care about the subgroups
     while scanner.skip(PARAM_RE)
+      key = scanner[:key]
+      # Detect a duplicate key
+      raise Mastodon::SignatureVerificationError, 'Error parsing signature with duplicate keys' if params.key?(key)
+
       # This is not actually correct with regards to quoted pairs, but it's consistent
       # with our previous implementation, and good enough in practice.
-      params[scanner[:key]] = scanner[:value] || scanner[:quoted_value][1...-1]
+      params[key] = scanner[:value] || scanner[:quoted_value][1...-1]
 
       scanner.skip(/\s*/)
       return params if scanner.eos?
diff --git a/app/services/batched_remove_status_service.rb b/app/services/batched_remove_status_service.rb
index 6ce29d7b8b..7fd9ced772 100644
--- a/app/services/batched_remove_status_service.rb
+++ b/app/services/batched_remove_status_service.rb
@@ -34,7 +34,7 @@ class BatchedRemoveStatusService < BaseService
     # transaction lock the database, but we use the delete method instead
     # of destroy to avoid all callbacks. We rely on foreign keys to
     # cascade the delete faster without loading the associations.
-    statuses_and_reblogs.each_slice(50) { |slice| Status.where(id: slice.map(&:id)).delete_all }
+    statuses_and_reblogs.each_slice(50) { |slice| Status.unscoped.where(id: slice.pluck(:id)).delete_all }
 
     # Since we skipped all callbacks, we also need to manually
     # deindex the statuses