diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4ca07afcc..583704e50 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,23 @@ Changelog
 
 All notable changes to this project will be documented in this file.
 
+## End of life notice
+
+**The 4.0.x branch will not receive any update after 2023-10-31.**
+This means that no security fix will be made available for this branch after this date, and you will need to update to a more recent version (such as the 4.1.x branch) to receive security fixes.
+
+## [4.0.9] - 2023-09-05
+
+### Changed
+
+- Change remote report processing to accept reports with long comments, but truncate them ([ThisIsMissEm](https://github.com/mastodon/mastodon/pull/25028))
+
+### Fixed
+
+- **Fix blocking subdomains of an already-blocked domain** ([ClearlyClaire](https://github.com/mastodon/mastodon/pull/26392))
+- Fix `/api/v1/timelines/tag/:hashtag` allowing for unauthenticated access when public preview is disabled ([danielmbrasil](https://github.com/mastodon/mastodon/pull/26237))
+- Fix inefficiencies in `PlainTextFormatter` ([ClearlyClaire](https://github.com/mastodon/mastodon/pull/26727))
+
 ## [4.0.8] - 2023-07-31
 
 ### Fixed
diff --git a/SECURITY.md b/SECURITY.md
index ccc7c1034..ebb05ba2c 100644
--- a/SECURITY.md
+++ b/SECURITY.md
@@ -10,8 +10,9 @@ A "vulnerability in Mastodon" is a vulnerability in the code distributed through
 
 ## Supported Versions
 
-| Version | Supported |
-| ------- | ----------|
-| 4.0.x   | Yes       |
-| 3.5.x   | Yes       |
-| < 3.5   | No        |
+| Version | Supported          |
+| ------- | ------------------ |
+| 4.1.x   | Yes                |
+| 4.0.x   | Until 2023-10-31   |
+| 3.5.x   | Until 2023-12-31   |
+| < 3.5   | No                 |
diff --git a/docker-compose.yml b/docker-compose.yml
index 07368b9f9..2efd47d97 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -56,7 +56,7 @@ services:
 
   web:
     build: .
-    image: ghcr.io/mastodon/mastodon:v4.0.8
+    image: ghcr.io/mastodon/mastodon:v4.0.9
     restart: always
     env_file: .env.production
     command: bash -c "rm -f /mastodon/tmp/pids/server.pid; bundle exec rails s -p 3000"
@@ -77,7 +77,7 @@ services:
 
   streaming:
     build: .
-    image: ghcr.io/mastodon/mastodon:v4.0.8
+    image: ghcr.io/mastodon/mastodon:v4.0.9
     restart: always
     env_file: .env.production
     command: node ./streaming
@@ -95,7 +95,7 @@ services:
 
   sidekiq:
     build: .
-    image: ghcr.io/mastodon/mastodon:v4.0.8
+    image: ghcr.io/mastodon/mastodon:v4.0.9
     restart: always
     env_file: .env.production
     command: bundle exec sidekiq
diff --git a/lib/mastodon/version.rb b/lib/mastodon/version.rb
index 5edb88c45..873969cab 100644
--- a/lib/mastodon/version.rb
+++ b/lib/mastodon/version.rb
@@ -13,7 +13,7 @@ module Mastodon
     end
 
     def patch
-      8
+      9
     end
 
     def flags