diff --git a/CHANGELOG.md b/CHANGELOG.md
index 20e12f3ccd..76f40bd1d1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,13 @@
 
 All notable changes to this project will be documented in this file.
 
+## [4.3.15] - 2025-11-20
+
+### Fixed
+
+- Fix `tootctl upgrade storage-schema` failing with `ArgumentError` (#36914 by @shugo)
+- Fix old previously-undiscovered posts being treated as new when receiving an `Update` (#36848 by @ClearlyClaire)
+
 ## [4.3.14] - 2025-10-13
 
 ### Security
diff --git a/SECURITY.md b/SECURITY.md
index 19f431fac5..385c946512 100644
--- a/SECURITY.md
+++ b/SECURITY.md
@@ -16,6 +16,6 @@ A "vulnerability in Mastodon" is a vulnerability in the code distributed through
 | Version | Supported        |
 | ------- | ---------------- |
 | 4.4.x   | Yes              |
-| 4.3.x   | Yes              |
+| 4.3.x   | Until 2026-05-06 |
 | 4.2.x   | Until 2026-01-08 |
 | < 4.2   | No               |
diff --git a/app/lib/activitypub/activity/update.rb b/app/lib/activitypub/activity/update.rb
index 15025ca5e7..5185507bdc 100644
--- a/app/lib/activitypub/activity/update.rb
+++ b/app/lib/activitypub/activity/update.rb
@@ -1,6 +1,9 @@
 # frozen_string_literal: true
 
 class ActivityPub::Activity::Update < ActivityPub::Activity
+  # Updates to unknown objects older than that are ignored
+  OBJECT_AGE_THRESHOLD = 1.day
+
   def perform
     @account.schedule_refresh_if_stale!
 
@@ -28,6 +31,9 @@ class ActivityPub::Activity::Update < ActivityPub::Activity
 
     @status = Status.find_by(uri: object_uri, account_id: @account.id)
 
+    # Ignore updates for old unknown objects, since those are updates we are not interested in
+    return if @status.nil? && object_too_old?
+
     # We may be getting `Create` and `Update` out of order
     @status ||= ActivityPub::Activity::Create.new(@json, @account, **@options).perform
 
@@ -35,4 +41,10 @@ class ActivityPub::Activity::Update < ActivityPub::Activity
 
     ActivityPub::ProcessStatusUpdateService.new.call(@status, @json, @object, request_id: @options[:request_id])
   end
+
+  def object_too_old?
+    @object['published'].present? && @object['published'].to_datetime < OBJECT_AGE_THRESHOLD.ago
+  rescue Date::Error
+    false
+  end
 end
diff --git a/docker-compose.yml b/docker-compose.yml
index 483a9b5893..c329baf7e7 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:v4.3.14
+    image: ghcr.io/glitch-soc/mastodon:v4.3.15
     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:v4.3.14
+    image: ghcr.io/glitch-soc/mastodon-streaming:v4.3.15
     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:v4.3.14
+    image: ghcr.io/glitch-soc/mastodon:v4.3.15
     restart: always
     env_file: .env.production
     command: bundle exec sidekiq
diff --git a/lib/mastodon/cli/upgrade.rb b/lib/mastodon/cli/upgrade.rb
index 2cb5105794..d5822cacc0 100644
--- a/lib/mastodon/cli/upgrade.rb
+++ b/lib/mastodon/cli/upgrade.rb
@@ -123,12 +123,12 @@ module Mastodon::CLI
         progress.log("Moving #{previous_path} to #{upgraded_path}") if options[:verbose]
 
         begin
-          move_previous_to_upgraded
+          move_previous_to_upgraded(previous_path, upgraded_path)
         rescue => e
           progress.log(pastel.red("Error processing #{previous_path}: #{e}"))
           success = false
 
-          remove_directory
+          remove_directory(upgraded_path)
         end
       end
 
diff --git a/lib/mastodon/version.rb b/lib/mastodon/version.rb
index 3c4954e82e..cdef58d7a9 100644
--- a/lib/mastodon/version.rb
+++ b/lib/mastodon/version.rb
@@ -13,7 +13,7 @@ module Mastodon
     end
 
     def patch
-      14
+      15
     end
 
     def default_prerelease
diff --git a/yarn.lock b/yarn.lock
index bca7819f05..a7ee30ee27 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -9087,8 +9087,8 @@ __metadata:
   linkType: hard
 
 "glob@npm:^10.2.2, glob@npm:^10.2.6, glob@npm:^10.3.10":
-  version: 10.4.5
-  resolution: "glob@npm:10.4.5"
+  version: 10.5.0
+  resolution: "glob@npm:10.5.0"
   dependencies:
     foreground-child: "npm:^3.1.0"
     jackspeak: "npm:^3.1.2"
@@ -9098,7 +9098,7 @@ __metadata:
     path-scurry: "npm:^1.11.1"
   bin:
     glob: dist/esm/bin.mjs
-  checksum: 10c0/19a9759ea77b8e3ca0a43c2f07ecddc2ad46216b786bb8f993c445aee80d345925a21e5280c7b7c6c59e860a0154b84e4b2b60321fea92cd3c56b4a7489f160e
+  checksum: 10c0/100705eddbde6323e7b35e1d1ac28bcb58322095bd8e63a7d0bef1a2cdafe0d0f7922a981b2b48369a4f8c1b077be5c171804534c3509dfe950dde15fbe6d828
   languageName: node
   linkType: hard