diff --git a/.browserslistrc b/.browserslistrc
index d5734664cc..54dd3aaf34 100644
--- a/.browserslistrc
+++ b/.browserslistrc
@@ -4,6 +4,4 @@ not IE 11
 not dead
 
 [development]
-last 1 chrome version
-last 1 firefox version
-last 1 safari version
+supports es6-module
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 841c01bfb9..ed4cdd881a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,53 @@ Changelog
 
 All notable changes to this project will be documented in this file.
 
+## [3.5.3] - 2022-05-26
+### Added
+
+- **Add language dropdown to compose form in web UI** ([Gargron](https://github.com/mastodon/mastodon/pull/18420), [ykzts](https://github.com/mastodon/mastodon/pull/18460))
+- **Add warning for limited accounts in web UI** ([Gargron](https://github.com/mastodon/mastodon/pull/18344))
+- Add `limited` attribute to accounts in REST API ([Gargron](https://github.com/mastodon/mastodon/pull/18344))
+
+### Changed
+
+- **Change RSS feeds** ([Gargron](https://github.com/mastodon/mastodon/pull/18356), [tribela](https://github.com/mastodon/mastodon/pull/18406))
+  - Titles are now date and time of post
+  - Bodies now render all content faithfully, including polls and emojis
+  - All media attachments are included with Media RSS
+- Change "dangerous" to "sensitive" in privacy policy and web UI ([Gargron](https://github.com/mastodon/mastodon/pull/18515))
+- Change unconfirmed accounts to not be visible in REST API ([ClearlyClaire](https://github.com/mastodon/mastodon/pull/17530))
+- Change `tootctl search deploy` to improve performance ([Gargron](https://github.com/mastodon/mastodon/pull/18463), [Gargron](https://github.com/mastodon/mastodon/pull/18514))
+- Change search indexing to use batches to minimize resource usage ([Gargron](https://github.com/mastodon/mastodon/pull/18451))
+
+### Fixed
+
+- Fix follower and other counters being able to go negative ([Gargron](https://github.com/mastodon/mastodon/pull/18517))
+- Fix unnecessary query on when creating a status ([ClearlyClaire](https://github.com/mastodon/mastodon/pull/17901))
+- Fix warning an account outside of a report closing all reports for that account ([ClearlyClaire](https://github.com/mastodon/mastodon/pull/18387))
+- Fix error when resolving a link that redirects to a local post ([ClearlyClaire](https://github.com/mastodon/mastodon/pull/18314))
+- Fix preferred posting language returning unusable value in REST API ([Gargron](https://github.com/mastodon/mastodon/pull/18428))
+- Fix race condition error when external status is reblogged ([ykzts](https://github.com/mastodon/mastodon/pull/18424))
+- Fix missing string for appeal validation error ([Gargron](https://github.com/mastodon/mastodon/pull/18410))
+- Fix block/mute lists showing a follow button in web UI ([ClearlyClaire](https://github.com/mastodon/mastodon/pull/18364))
+- Fix Redis configuration not being changed by `mastodon:setup` ([ClearlyClaire](https://github.com/mastodon/mastodon/pull/18383))
+- Fix streaming notifications not using quick filter logic in web UI ([ClearlyClaire](https://github.com/mastodon/mastodon/pull/18316))
+- Fix ambiguous wording on appeal actions in admin UI ([ClearlyClaire](https://github.com/mastodon/mastodon/pull/18328))
+- Fix floating action button obscuring last element in web UI ([ClearlyClaire](https://github.com/mastodon/mastodon/pull/18332))
+- Fix account warnings not being recorded in audit log ([ClearlyClaire](https://github.com/mastodon/mastodon/pull/18338))
+- Fix leftover icons for direct visibility statuses ([Steffo99](https://github.com/mastodon/mastodon/pull/18305))
+- Fix link verification requiring case sensitivity on links ([sgolemon](https://github.com/mastodon/mastodon/pull/18320))
+- Fix embeds not setting their height correctly ([rinsuki](https://github.com/mastodon/mastodon/pull/18301))
+
+### Security
+
+- Fix concurrent unfollowing decrementing follower count more than once ([Gargron](https://github.com/mastodon/mastodon/pull/18527))
+- Fix being able to appeal a strike unlimited times ([Gargron](https://github.com/mastodon/mastodon/pull/18529))
+- Fix being able to report otherwise inaccessible statuses ([Gargron](https://github.com/mastodon/mastodon/pull/18528))
+- Fix empty votes arbitrarily increasing voters count in polls ([Gargron](https://github.com/mastodon/mastodon/pull/18526))
+- Fix moderator identity leak when approving appeal of sensitive marked statuses ([Gargron](https://github.com/mastodon/mastodon/pull/18525))
+- Fix suspended users being able to access APIs that don't require a user ([Gargron](https://github.com/mastodon/mastodon/pull/18524))
+- Fix confirmation redirect to app without `Location` header ([Gargron](https://github.com/mastodon/mastodon/pull/18523))
+
 ## [3.5.2] - 2022-05-04
 ### Added
 
diff --git a/SECURITY.md b/SECURITY.md
index 12f50ed880..62e23f7360 100644
--- a/SECURITY.md
+++ b/SECURITY.md
@@ -14,7 +14,7 @@ A "vulnerability in Mastodon" is a vulnerability in the code distributed through
 | ------- | ------------------ |
 | 3.5.x   | Yes                |
 | 3.4.x   | Yes                |
-| 3.3.x   | Yes                |
+| 3.3.x   | No                 |
 | < 3.3   | No                 |
 
 [bug-bounty]: https://app.intigriti.com/programs/mastodon/mastodonio/detail
diff --git a/app/controllers/activitypub/base_controller.rb b/app/controllers/activitypub/base_controller.rb
index 196d85a326..b8a7e0ab96 100644
--- a/app/controllers/activitypub/base_controller.rb
+++ b/app/controllers/activitypub/base_controller.rb
@@ -2,6 +2,7 @@
 
 class ActivityPub::BaseController < Api::BaseController
   skip_before_action :require_authenticated_user!
+  skip_before_action :require_not_suspended!
   skip_around_action :set_locale
 
   private
diff --git a/app/controllers/api/base_controller.rb b/app/controllers/api/base_controller.rb
index d96285b440..2e393fbb6f 100644
--- a/app/controllers/api/base_controller.rb
+++ b/app/controllers/api/base_controller.rb
@@ -11,6 +11,7 @@ class Api::BaseController < ApplicationController
   skip_before_action :require_functional!, unless: :whitelist_mode?
 
   before_action :require_authenticated_user!, if: :disallow_unauthenticated_api_access?
+  before_action :require_not_suspended!
   before_action :set_cache_headers
 
   protect_from_forgery with: :null_session
@@ -97,6 +98,10 @@ class Api::BaseController < ApplicationController
     render json: { error: 'This method requires an authenticated user' }, status: 401 unless current_user
   end
 
+  def require_not_suspended!
+    render json: { error: 'Your login is currently disabled' }, status: 403 if current_user&.account&.suspended?
+  end
+
   def require_user!
     if !current_user
       render json: { error: 'This method requires an authenticated user' }, status: 422
diff --git a/app/controllers/auth/confirmations_controller.rb b/app/controllers/auth/confirmations_controller.rb
index 17ad56fa87..0817a905ca 100644
--- a/app/controllers/auth/confirmations_controller.rb
+++ b/app/controllers/auth/confirmations_controller.rb
@@ -89,7 +89,7 @@ class Auth::ConfirmationsController < Devise::ConfirmationsController
 
   def after_confirmation_path_for(_resource_name, user)
     if user.created_by_application && truthy_param?(:redirect_to_app)
-      user.created_by_application.redirect_uri
+      user.created_by_application.confirmation_redirect_uri
     else
       super
     end
diff --git a/app/helpers/formatting_helper.rb b/app/helpers/formatting_helper.rb
index 526efd766f..448177bec2 100644
--- a/app/helpers/formatting_helper.rb
+++ b/app/helpers/formatting_helper.rb
@@ -23,7 +23,7 @@ module FormattingHelper
 
     before_html = begin
       if status.spoiler_text?
-        "<p><strong>#{I18n.t('rss.content_warning', locale: valid_locale_or_nil(status.language))}</strong> #{h(status.spoiler_text)}</p><hr />"
+        "<p><strong>#{I18n.t('rss.content_warning', locale: available_locale_or_nil(status.language) || I18n.default_locale)}</strong> #{h(status.spoiler_text)}</p><hr />"
       else
         ''
       end
diff --git a/app/helpers/languages_helper.rb b/app/helpers/languages_helper.rb
index d39bb6c930..4077e19bdf 100644
--- a/app/helpers/languages_helper.rb
+++ b/app/helpers/languages_helper.rb
@@ -254,4 +254,8 @@ module LanguagesHelper
   def valid_locale?(locale)
     locale.present? && SUPPORTED_LOCALES.key?(locale.to_sym)
   end
+
+  def available_locale_or_nil(locale_name)
+    locale_name.to_sym if locale_name.present? && I18n.available_locales.include?(locale_name.to_sym)
+  end
 end
diff --git a/app/lib/application_extension.rb b/app/lib/application_extension.rb
index a1fea6430a..d61ec0e6e7 100644
--- a/app/lib/application_extension.rb
+++ b/app/lib/application_extension.rb
@@ -12,4 +12,8 @@ module ApplicationExtension
   def most_recently_used_access_token
     @most_recently_used_access_token ||= access_tokens.where.not(last_used_at: nil).order(last_used_at: :desc).first
   end
+
+  def confirmation_redirect_uri
+    redirect_uri.lines.first.strip
+  end
 end
diff --git a/app/lib/rss/media_content.rb b/app/lib/rss/media_content.rb
index 7aefd8b40b..f281fe29e4 100644
--- a/app/lib/rss/media_content.rb
+++ b/app/lib/rss/media_content.rb
@@ -26,4 +26,10 @@ class RSS::MediaContent < RSS::Element
       description['type'] = 'plain'
     end
   end
+
+  def thumbnail(str)
+    append_element('media:thumbnail') do |thumbnail|
+      thumbnail['url'] = str
+    end
+  end
 end
diff --git a/app/models/account_stat.rb b/app/models/account_stat.rb
index b49827267a..a5d71a5b8c 100644
--- a/app/models/account_stat.rb
+++ b/app/models/account_stat.rb
@@ -20,4 +20,16 @@ class AccountStat < ApplicationRecord
   belongs_to :account, inverse_of: :account_stat
 
   update_index('accounts', :account)
+
+  def following_count
+    [attributes['following_count'], 0].max
+  end
+
+  def followers_count
+    [attributes['followers_count'], 0].max
+  end
+
+  def statuses_count
+    [attributes['statuses_count'], 0].max
+  end
 end
diff --git a/app/models/admin/status_batch_action.rb b/app/models/admin/status_batch_action.rb
index 631af183c2..7bf6fa6daf 100644
--- a/app/models/admin/status_batch_action.rb
+++ b/app/models/admin/status_batch_action.rb
@@ -103,7 +103,7 @@ class Admin::StatusBatchAction
 
   def handle_report!
     @report = Report.new(report_params) unless with_report?
-    @report.status_ids = (@report.status_ids + status_ids.map(&:to_i)).uniq
+    @report.status_ids = (@report.status_ids + allowed_status_ids).uniq
     @report.save!
 
     @report_id = @report.id
@@ -135,4 +135,8 @@ class Admin::StatusBatchAction
   def report_params
     { account: current_account, target_account: target_account }
   end
+
+  def allowed_status_ids
+    AccountStatusesFilter.new(@report.target_account, current_account).results.with_discarded.where(id: status_ids).pluck(:id)
+  end
 end
diff --git a/app/models/status_stat.rb b/app/models/status_stat.rb
index 024c467e71..437861d1c4 100644
--- a/app/models/status_stat.rb
+++ b/app/models/status_stat.rb
@@ -17,6 +17,18 @@ class StatusStat < ApplicationRecord
 
   after_commit :reset_parent_cache
 
+  def replies_count
+    [attributes['replies_count'], 0].max
+  end
+
+  def reblogs_count
+    [attributes['reblogs_count'], 0].max
+  end
+
+  def favourites_count
+    [attributes['favourites_count'], 0].max
+  end
+
   private
 
   def reset_parent_cache
diff --git a/app/services/appeal_service.rb b/app/services/appeal_service.rb
index 1397c50f5f..cef9be05fd 100644
--- a/app/services/appeal_service.rb
+++ b/app/services/appeal_service.rb
@@ -14,7 +14,8 @@ class AppealService < BaseService
   private
 
   def create_appeal!
-    @appeal = @strike.create_appeal!(
+    @appeal = Appeal.create!(
+      strike: @strike,
       text: @text,
       account: @strike.target_account
     )
diff --git a/app/services/approve_appeal_service.rb b/app/services/approve_appeal_service.rb
index 37a08b46e3..96aaaa7d07 100644
--- a/app/services/approve_appeal_service.rb
+++ b/app/services/approve_appeal_service.rb
@@ -52,8 +52,9 @@ class ApproveAppealService < BaseService
   end
 
   def undo_mark_statuses_as_sensitive!
+    representative_account = Account.representative
     @strike.statuses.includes(:media_attachments).each do |status|
-      UpdateStatusService.new.call(status, @current_account.id, sensitive: false) if status.with_media?
+      UpdateStatusService.new.call(status, representative_account.id, sensitive: false) if status.with_media?
     end
   end
 
diff --git a/app/services/report_service.rb b/app/services/report_service.rb
index 9d784c341a..d251bb33f0 100644
--- a/app/services/report_service.rb
+++ b/app/services/report_service.rb
@@ -57,7 +57,7 @@ class ReportService < BaseService
   end
 
   def reported_status_ids
-    @target_account.statuses.with_discarded.find(Array(@status_ids)).pluck(:id)
+    AccountStatusesFilter.new(@target_account, @source_account).results.with_discarded.find(Array(@status_ids)).pluck(:id)
   end
 
   def payload
diff --git a/app/services/unfollow_service.rb b/app/services/unfollow_service.rb
index 151f3674fd..d83a60e4e7 100644
--- a/app/services/unfollow_service.rb
+++ b/app/services/unfollow_service.rb
@@ -2,6 +2,8 @@
 
 class UnfollowService < BaseService
   include Payloadable
+  include Redisable
+  include Lockable
 
   # Unfollow and notify the remote user
   # @param [Account] source_account Where to unfollow from
@@ -13,7 +15,9 @@ class UnfollowService < BaseService
     @target_account = target_account
     @options        = options
 
-    unfollow! || undo_follow_request!
+    with_lock("relationship:#{[source_account.id, target_account.id].sort.join(':')}") do
+      unfollow! || undo_follow_request!
+    end
   end
 
   private
diff --git a/app/services/vote_service.rb b/app/services/vote_service.rb
index ccd04dbfcb..114ec285c8 100644
--- a/app/services/vote_service.rb
+++ b/app/services/vote_service.rb
@@ -7,6 +7,8 @@ class VoteService < BaseService
   include Lockable
 
   def call(account, poll, choices)
+    return if choices.empty?
+
     authorize_with account, poll, :vote?
 
     @account = account
diff --git a/config/initializers/doorkeeper.rb b/config/initializers/doorkeeper.rb
index f78db86534..84b649f5c1 100644
--- a/config/initializers/doorkeeper.rb
+++ b/config/initializers/doorkeeper.rb
@@ -128,6 +128,13 @@ Doorkeeper.configure do
   #
   force_ssl_in_redirect_uri false
 
+  # Specify what redirect URI's you want to block during Application creation.
+  # Any redirect URI is whitelisted by default.
+  #
+  # You can use this option in order to forbid URI's with 'javascript' scheme
+  # for example.
+  forbid_redirect_uri { |uri| %w[data vbscript javascript].include?(uri.scheme.to_s.downcase) }
+
   # Specify what grant flows are enabled in array of Strings. The valid
   # strings and the flows they enable are:
   #
diff --git a/lib/mastodon/version.rb b/lib/mastodon/version.rb
index bc22539d9c..2d0b283230 100644
--- a/lib/mastodon/version.rb
+++ b/lib/mastodon/version.rb
@@ -13,7 +13,7 @@ module Mastodon
     end
 
     def patch
-      2
+      3
     end
 
     def flags