diff --git a/SECURITY.md b/SECURITY.md
index 12052652e6..e5790a66fa 100644
--- a/SECURITY.md
+++ b/SECURITY.md
@@ -18,5 +18,4 @@ A "vulnerability in Mastodon" is a vulnerability in the code distributed through
 | 4.5.x   | Yes              |
 | 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/api/v1/statuses_controller.rb b/app/controllers/api/v1/statuses_controller.rb
index 370fbacbf4..1a153accf3 100644
--- a/app/controllers/api/v1/statuses_controller.rb
+++ b/app/controllers/api/v1/statuses_controller.rb
@@ -107,9 +107,7 @@ class Api::V1::StatusesController < Api::BaseController
     @status = Status.where(account: current_account).find(params[:id])
     authorize @status, :update?
 
-    UpdateStatusService.new.call(
-      @status,
-      current_account.id,
+    update_options = {
       text: status_params[:status],
       media_ids: status_params[:media_ids],
       media_attributes: status_params[:media_attributes],
@@ -117,9 +115,12 @@ class Api::V1::StatusesController < Api::BaseController
       language: status_params[:language],
       spoiler_text: status_params[:spoiler_text],
       poll: status_params[:poll],
-      quote_approval_policy: quote_approval_policy,
-      content_type: status_params[:content_type]
-    )
+      content_type: status_params[:content_type],
+    }
+
+    update_options[:quote_approval_policy] = quote_approval_policy if status_params[:quote_approval_policy].present?
+
+    UpdateStatusService.new.call(@status, current_account.id, update_options)
 
     render json: @status, serializer: REST::StatusSerializer
   end
diff --git a/app/controllers/concerns/cache_concern.rb b/app/controllers/concerns/cache_concern.rb
index b1b09f2aab..3527cdaca0 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/javascript/flavours/glitch/features/emoji/normalize.test.ts b/app/javascript/flavours/glitch/features/emoji/normalize.test.ts
index b4c7669961..8222ab81e5 100644
--- a/app/javascript/flavours/glitch/features/emoji/normalize.test.ts
+++ b/app/javascript/flavours/glitch/features/emoji/normalize.test.ts
@@ -33,6 +33,7 @@ describe('emojiToUnicodeHex', () => {
     ['⚫', '26AB'],
     ['🖤', '1F5A4'],
     ['💀', '1F480'],
+    ['❤️', '2764'], // Checks for trailing variation selector removal.
     ['💂‍♂️', '1F482-200D-2642-FE0F'],
   ] as const)(
     'emojiToUnicodeHex converts %s to %s',
diff --git a/app/javascript/flavours/glitch/features/emoji/normalize.ts b/app/javascript/flavours/glitch/features/emoji/normalize.ts
index f0a502dcb5..d8aa1c29f0 100644
--- a/app/javascript/flavours/glitch/features/emoji/normalize.ts
+++ b/app/javascript/flavours/glitch/features/emoji/normalize.ts
@@ -30,6 +30,12 @@ export function emojiToUnicodeHex(emoji: string): string {
       codes.push(code);
     }
   }
+
+  // Handles how Emojibase removes the variation selector for single code emojis.
+  // See: https://emojibase.dev/docs/spec/#merged-variation-selectors
+  if (codes.at(1) === VARIATION_SELECTOR_CODE && codes.length === 2) {
+    codes.pop();
+  }
   return hexNumbersToString(codes);
 }
 
diff --git a/app/javascript/flavours/glitch/styles/admin.scss b/app/javascript/flavours/glitch/styles/admin.scss
index 3199358730..7a36db424c 100644
--- a/app/javascript/flavours/glitch/styles/admin.scss
+++ b/app/javascript/flavours/glitch/styles/admin.scss
@@ -163,6 +163,7 @@ $content-width: 840px;
     width: 100%;
     max-width: $content-width;
     flex: 1 1 auto;
+    isolation: isolate;
   }
 
   @media screen and (max-width: ($content-width + $sidebar-width)) {
diff --git a/app/javascript/mastodon/features/emoji/normalize.test.ts b/app/javascript/mastodon/features/emoji/normalize.test.ts
index b4c7669961..8222ab81e5 100644
--- a/app/javascript/mastodon/features/emoji/normalize.test.ts
+++ b/app/javascript/mastodon/features/emoji/normalize.test.ts
@@ -33,6 +33,7 @@ describe('emojiToUnicodeHex', () => {
     ['⚫', '26AB'],
     ['🖤', '1F5A4'],
     ['💀', '1F480'],
+    ['❤️', '2764'], // Checks for trailing variation selector removal.
     ['💂‍♂️', '1F482-200D-2642-FE0F'],
   ] as const)(
     'emojiToUnicodeHex converts %s to %s',
diff --git a/app/javascript/mastodon/features/emoji/normalize.ts b/app/javascript/mastodon/features/emoji/normalize.ts
index a09505e97f..59304c89e8 100644
--- a/app/javascript/mastodon/features/emoji/normalize.ts
+++ b/app/javascript/mastodon/features/emoji/normalize.ts
@@ -30,6 +30,12 @@ export function emojiToUnicodeHex(emoji: string): string {
       codes.push(code);
     }
   }
+
+  // Handles how Emojibase removes the variation selector for single code emojis.
+  // See: https://emojibase.dev/docs/spec/#merged-variation-selectors
+  if (codes.at(1) === VARIATION_SELECTOR_CODE && codes.length === 2) {
+    codes.pop();
+  }
   return hexNumbersToString(codes);
 }
 
diff --git a/app/javascript/styles/mastodon/admin.scss b/app/javascript/styles/mastodon/admin.scss
index 8f892ce209..04c86ce834 100644
--- a/app/javascript/styles/mastodon/admin.scss
+++ b/app/javascript/styles/mastodon/admin.scss
@@ -163,6 +163,7 @@ $content-width: 840px;
     width: 100%;
     max-width: $content-width;
     flex: 1 1 auto;
+    isolation: isolate;
   }
 
   @media screen and (max-width: ($content-width + $sidebar-width)) {
diff --git a/app/lib/activitypub/activity.rb b/app/lib/activitypub/activity.rb
index 64ee9acd05..d07d1c2f24 100644
--- a/app/lib/activitypub/activity.rb
+++ b/app/lib/activitypub/activity.rb
@@ -21,14 +21,13 @@ class ActivityPub::Activity
 
   class << self
     def factory(json, account, **)
-      @json = json
-      klass&.new(json, account, **)
+      klass_for(json)&.new(json, account, **)
     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/activitypub/activity/quote_request.rb b/app/lib/activitypub/activity/quote_request.rb
index 12f48ebb2b..46c45cde27 100644
--- a/app/lib/activitypub/activity/quote_request.rb
+++ b/app/lib/activitypub/activity/quote_request.rb
@@ -47,7 +47,7 @@ class ActivityPub::Activity::QuoteRequest < ActivityPub::Activity
     # NOTE: Replacing the object's context by that of the parent activity is
     # not sound, but it's consistent with the rest of the codebase
     instrument = @json['instrument'].merge({ '@context' => @json['@context'] })
-    return if non_matching_uri_hosts?(instrument['id'], @account.uri)
+    return if non_matching_uri_hosts?(@account.uri, instrument['id'])
 
     ActivityPub::FetchRemoteStatusService.new.call(instrument['id'], prefetched_body: instrument, on_behalf_of: quoted_status.account, request_id: @options[:request_id])
   end
diff --git a/app/lib/activitypub/tag_manager.rb b/app/lib/activitypub/tag_manager.rb
index 43574d3657..3174d1792e 100644
--- a/app/lib/activitypub/tag_manager.rb
+++ b/app/lib/activitypub/tag_manager.rb
@@ -50,7 +50,7 @@ class ActivityPub::TagManager
       context_url(target) unless target.parent_account_id.nil? || target.parent_status_id.nil?
     when :note, :comment, :activity
       if target.account.numeric_ap_id?
-        return activity_ap_account_status_url(target.account, target) if target.reblog?
+        return activity_ap_account_status_url(target.account.id, target) if target.reblog?
 
         ap_account_status_url(target.account.id, target)
       else
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 fde31ad757..62a5563553 100644
--- a/app/lib/feed_manager.rb
+++ b/app/lib/feed_manager.rb
@@ -500,6 +500,7 @@ 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 9326eed26c..9071543b63 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
diff --git a/spec/lib/activitypub/tag_manager_spec.rb b/spec/lib/activitypub/tag_manager_spec.rb
index cad46ad903..6cbb58055e 100644
--- a/spec/lib/activitypub/tag_manager_spec.rb
+++ b/spec/lib/activitypub/tag_manager_spec.rb
@@ -128,6 +128,28 @@ RSpec.describe ActivityPub::TagManager do
             .to eq("#{host_prefix}/ap/users/#{status.account.id}/statuses/#{status.id}")
         end
       end
+
+      context 'with a reblog' do
+        let(:status) { Fabricate(:status, account:, reblog: Fabricate(:status)) }
+
+        context 'when using a numeric ID based scheme' do
+          let(:account) { Fabricate(:account, id_scheme: :numeric_ap_id) }
+
+          it 'returns a string starting with web domain and with the expected path' do
+            expect(subject.uri_for(status))
+              .to eq("#{host_prefix}/ap/users/#{status.account.id}/statuses/#{status.id}/activity")
+          end
+        end
+
+        context 'when using the legacy username based scheme' do
+          let(:account) { Fabricate(:account, id_scheme: :username_ap_id) }
+
+          it 'returns a string starting with web domain and with the expected path' do
+            expect(subject.uri_for(status))
+              .to eq("#{host_prefix}/users/#{status.account.username}/statuses/#{status.id}/activity")
+          end
+        end
+      end
     end
 
     context 'with a remote status' do
diff --git a/spec/requests/api/v1/statuses_spec.rb b/spec/requests/api/v1/statuses_spec.rb
index 2cb67272b7..a89be2aa25 100644
--- a/spec/requests/api/v1/statuses_spec.rb
+++ b/spec/requests/api/v1/statuses_spec.rb
@@ -508,6 +508,15 @@ RSpec.describe '/api/v1/statuses' do
             .to start_with('application/json')
         end
       end
+
+      context 'when status has non-default quote policy and param is omitted' do
+        let(:status) { Fabricate(:status, account: user.account, quote_approval_policy: 'nobody') }
+
+        it 'preserves existing quote approval policy' do
+          expect { subject }
+            .to_not(change { status.reload.quote_approval_policy })
+        end
+      end
     end
   end