diff --git a/CHANGELOG.md b/CHANGELOG.md
index 399b2fe084..8c5ec67d85 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,31 @@
 
 All notable changes to this project will be documented in this file.
 
+## [4.5.4] - 2026-01-07
+
+### Security
+
+- Fix SSRF protection bypass ([GHSA](https://github.com/mastodon/mastodon/security/advisories/GHSA-xfrj-c749-jxxq))
+- Fix missing ownership check in severed relationships controller ([GHSA](https://github.com/mastodon/mastodon/security/advisories/GHSA-ww85-x9cp-5v24))
+
+### Changed
+
+- Change HTTP Signature verification status from 401 to 503 on temporary failure to get remote actor (#37221 by @ClearlyClaire)
+
+### Fixed
+
+- Fix custom emojis not being rendered in profile fields (#37365 by @ClearlyClaire)
+- Fix serialization of context pages (#37376 by @ClearlyClaire)
+- Fix quotes with CWs but no text not having fallback link (#37361 by @ClearlyClaire)
+- Fix outdated link target for “locked” warning (#37366 by @ClearlyClaire)
+- Fix local custom emojis sometimes being rendered in remote posts (#37284 by @ChaosExAnima)
+- Fix some assets not being loaded from configured CDN (#37310 by @ChaosExAnima)
+- Fix notifications page error in Tor browser (#37285 by @diondiondion)
+- Fix custom emojis not being displayed in CWs and fav/boost notifications (#37272 and #37306 by @ChaosExAnima and @ClearlyClaire)
+- Fix default `Admin` role not including `view_feeds` permission (#37301 by @ClearlyClaire)
+- Fix hashtag autocomplete replacing suggestion's first characters with input (#37281 by @ClearlyClaire)
+- Fix mentions of domain-blocked users being processed (#37257 by @ClearlyClaire)
+
 ## [4.5.3] - 2025-12-08
 
 ### Security
diff --git a/Gemfile.lock b/Gemfile.lock
index 743f0d5bcd..d9e2419e64 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -821,7 +821,7 @@ GEM
     sidekiq-scheduler (6.0.1)
       rufus-scheduler (~> 3.2)
       sidekiq (>= 7.3, < 9)
-    sidekiq-unique-jobs (8.0.12)
+    sidekiq-unique-jobs (8.0.11)
       concurrent-ruby (~> 1.0, >= 1.0.5)
       sidekiq (>= 7.0.0, < 9.0.0)
       thor (>= 1.0, < 3.0)
diff --git a/app/controllers/severed_relationships_controller.rb b/app/controllers/severed_relationships_controller.rb
index 817abebf62..9371ebf7d0 100644
--- a/app/controllers/severed_relationships_controller.rb
+++ b/app/controllers/severed_relationships_controller.rb
@@ -26,7 +26,7 @@ class SeveredRelationshipsController < ApplicationController
   private
 
   def set_event
-    @event = AccountRelationshipSeveranceEvent.find(params[:id])
+    @event = AccountRelationshipSeveranceEvent.where(account: current_account).find(params[:id])
   end
 
   def following_data
diff --git a/app/lib/private_address_check.rb b/app/lib/private_address_check.rb
index d00b16e66b..5c4db6ffae 100644
--- a/app/lib/private_address_check.rb
+++ b/app/lib/private_address_check.rb
@@ -1,9 +1,7 @@
 # frozen_string_literal: true
 
 module PrivateAddressCheck
-  module_function
-
-  CIDR_LIST = [
+  IP4_CIDR_LIST = [
     IPAddr.new('0.0.0.0/8'),       # Current network (only valid as source address)
     IPAddr.new('100.64.0.0/10'),   # Shared Address Space
     IPAddr.new('172.16.0.0/12'),   # Private network
@@ -16,6 +14,9 @@ module PrivateAddressCheck
     IPAddr.new('224.0.0.0/4'),     # IP multicast (former Class D network)
     IPAddr.new('240.0.0.0/4'),     # Reserved (former Class E network)
     IPAddr.new('255.255.255.255'), # Broadcast
+  ].freeze
+
+  CIDR_LIST = (IP4_CIDR_LIST + IP4_CIDR_LIST.map(&:ipv4_mapped) + [
     IPAddr.new('64:ff9b::/96'),    # IPv4/IPv6 translation (RFC 6052)
     IPAddr.new('100::/64'),        # Discard prefix (RFC 6666)
     IPAddr.new('2001::/32'),       # Teredo tunneling
@@ -25,7 +26,9 @@ module PrivateAddressCheck
     IPAddr.new('2002::/16'),       # 6to4
     IPAddr.new('fc00::/7'),        # Unique local address
     IPAddr.new('ff00::/8'),        # Multicast
-  ].freeze
+  ]).freeze
+
+  module_function
 
   def private_address?(address)
     address.private? || address.loopback? || address.link_local? || CIDR_LIST.any? { |cidr| cidr.include?(address) }
diff --git a/docker-compose.yml b/docker-compose.yml
index fae93955f1..3615b745f1 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -59,7 +59,7 @@ services:
   web:
     # You can uncomment the following line if you want to not use the prebuilt image, for example if you have local code changes
     # build: .
-    image: ghcr.io/glitch-soc/mastodon:v4.5.3
+    image: ghcr.io/glitch-soc/mastodon:v4.5.4
     restart: always
     env_file: .env.production
     command: bundle exec puma -C config/puma.rb
@@ -83,7 +83,7 @@ services:
     # build:
     #   dockerfile: ./streaming/Dockerfile
     #   context: .
-    image: ghcr.io/glitch-soc/mastodon-streaming:v4.5.3
+    image: ghcr.io/glitch-soc/mastodon-streaming:v4.5.4
     restart: always
     env_file: .env.production
     command: node ./streaming/index.js
@@ -102,7 +102,7 @@ services:
   sidekiq:
     # You can uncomment the following line if you want to not use the prebuilt image, for example if you have local code changes
     # build: .
-    image: ghcr.io/glitch-soc/mastodon:v4.5.3
+    image: ghcr.io/glitch-soc/mastodon:v4.5.4
     restart: always
     env_file: .env.production
     command: bundle exec sidekiq
diff --git a/lib/mastodon/version.rb b/lib/mastodon/version.rb
index 9ac54d1b7c..235ac92cbd 100644
--- a/lib/mastodon/version.rb
+++ b/lib/mastodon/version.rb
@@ -17,7 +17,7 @@ module Mastodon
     end
 
     def default_prerelease
-      'alpha.1'
+      'alpha.2'
     end
 
     def prerelease
diff --git a/spec/lib/private_address_check_spec.rb b/spec/lib/private_address_check_spec.rb
new file mode 100644
index 0000000000..ee9f9295d5
--- /dev/null
+++ b/spec/lib/private_address_check_spec.rb
@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe PrivateAddressCheck do
+  describe 'private_address?' do
+    it 'returns true for private addresses' do
+      # rubocop:disable RSpec/ExpectActual
+      expect(
+        [
+          '192.168.1.7',
+          '0.0.0.0',
+          '127.0.0.1',
+          '::ffff:0.0.0.1',
+        ]
+      ).to all satisfy('return true') { |addr| described_class.private_address?(IPAddr.new(addr)) }
+      # rubocop:enable RSpec/ExpectActual
+    end
+  end
+end
diff --git a/spec/requests/severed_relationships_spec.rb b/spec/requests/severed_relationships_spec.rb
index ac98ab8f94..e0116120cb 100644
--- a/spec/requests/severed_relationships_spec.rb
+++ b/spec/requests/severed_relationships_spec.rb
@@ -3,9 +3,10 @@
 require 'rails_helper'
 
 RSpec.describe 'Severed Relationships' do
-  let(:account_rs_event) { Fabricate :account_relationship_severance_event }
+  let(:account_rs_event) { Fabricate(:account_relationship_severance_event) }
+  let(:user) { account_rs_event.account.user }
 
-  before { sign_in Fabricate(:user) }
+  before { sign_in user }
 
   describe 'GET /severed_relationships/:id/following' do
     it 'returns a CSV file with correct data' do
@@ -22,6 +23,17 @@ RSpec.describe 'Severed Relationships' do
       expect(response.body)
         .to include('Account address')
     end
+
+    context 'when the user is not the subject of the event' do
+      let(:user) { Fabricate(:user) }
+
+      it 'returns a 404' do
+        get following_severed_relationship_path(account_rs_event, format: :csv)
+
+        expect(response)
+          .to have_http_status(404)
+      end
+    end
   end
 
   describe 'GET /severed_relationships/:id/followers' do
@@ -39,5 +51,16 @@ RSpec.describe 'Severed Relationships' do
       expect(response.body)
         .to include('Account address')
     end
+
+    context 'when the user is not the subject of the event' do
+      let(:user) { Fabricate(:user) }
+
+      it 'returns a 404' do
+        get followers_severed_relationship_path(account_rs_event, format: :csv)
+
+        expect(response)
+          .to have_http_status(404)
+      end
+    end
   end
 end