diff --git a/_data/downloads.yml b/_data/downloads.yml
index 304c5eb86c..ac7fb19985 100644
--- a/_data/downloads.yml
+++ b/_data/downloads.yml
@@ -8,7 +8,7 @@ preview:
 stable:
 
   - 4.0.1
-  - 3.4.8
+  - 3.4.9
   - 3.3.10
   - 3.2.10
 
diff --git a/_data/releases.yml b/_data/releases.yml
index c7b95078f6..e528fa5129 100644
--- a/_data/releases.yml
+++ b/_data/releases.yml
@@ -165,6 +165,30 @@
 
 # 3.4 series
 
+- version: 3.4.9
+  date: 2026-03-11
+  post: "/en/news/2026/03/11/ruby-3-4-9-released/"
+  url:
+    gz: https://cache.ruby-lang.org/pub/ruby/3.4/ruby-3.4.9.tar.gz
+    xz: https://cache.ruby-lang.org/pub/ruby/3.4/ruby-3.4.9.tar.xz
+    zip: https://cache.ruby-lang.org/pub/ruby/3.4/ruby-3.4.9.zip
+  size:
+    gz: 22456968
+    xz: 16682004
+    zip: 27645906
+  sha1:
+    gz: 6386200753caf4e336dafceeee165fa73fd234ec
+    xz: 1eb1b0b45b9e9191de9d2f360164e60eedf77012
+    zip: 8c4312fe946c7eaa269e5c7cee90f3b7350235b5
+  sha256:
+    gz: 7bb4d4f5e807cc27251d14d9d6086d182c5b25875191e44ab15b709cd7a7dd9c
+    xz: 4231c54072601a171faed1699f105985e9971c94cd382b78feb4eb44eec2dd1a
+    zip: a4dd555fddefcdd4a58d2169a568f5887b125edbbda2815ea826ca1833dc41ec
+  sha512:
+    gz: ac7147c0e575cf74f669abb991ee8695d4191c919f306f124b3ee85d6b61361e752a4f1afb7bdffb49aee21edace1fcc9bf2b074ada15fa6c1eb611354c1d54b
+    xz: 356fb47cc56f2d25198cb95253fc20ff7d9a6fd1fa53bc475e5c440012aebe27562537c399d271357235114ade263fd625029b66cb0f9b526f9c04f169fb9580
+    zip: 1c6cc4d03edb071f79f9ae41d43defa8393b467d30000e89ee872c6fe99bde015421cb1dd3ecfd5f0359c1c095b60833a95cd5f6c4397358f8ed98eace8720e2
+
 - version: 3.4.8
   date: 2025-12-17
   post: /en/news/2025/12/17/ruby-3-4-8-released/
diff --git a/en/news/_posts/2026-03-11-ruby-3-4-9-released.md b/en/news/_posts/2026-03-11-ruby-3-4-9-released.md
new file mode 100644
index 0000000000..d3a18dbcc4
--- /dev/null
+++ b/en/news/_posts/2026-03-11-ruby-3-4-9-released.md
@@ -0,0 +1,47 @@
+---
+layout: news_post
+title: "Ruby 3.4.9 Released"
+author: nagachika
+translator:
+date: 2026-03-11 11:00:00 +0000
+lang: en
+---
+
+Ruby 3.4.9 has been released.
+
+This release includes [an update to the zlib gem addressing CVE-2026-27820](https://www.ruby-lang.org/en/news/2026/03/05/buffer-overflow-zlib-cve-2026-27820/),
+along with other bug fixes.
+Please see the [GitHub releases](https://github.com/ruby/ruby/releases/tag/v3_4_9) for further details.
+
+We recommend updating your version of the zlib gem. This release has been made for the convenience of those who wish to continue using it as a default gem.
+
+
+## Download
+
+{% assign release = site.data.releases | where: "version", "3.4.9" | first %}
+
+* <{{ release.url.gz }}>
+
+      SIZE: {{ release.size.gz }}
+      SHA1: {{ release.sha1.gz }}
+      SHA256: {{ release.sha256.gz }}
+      SHA512: {{ release.sha512.gz }}
+
+* <{{ release.url.xz }}>
+
+      SIZE: {{ release.size.xz }}
+      SHA1: {{ release.sha1.xz }}
+      SHA256: {{ release.sha256.xz }}
+      SHA512: {{ release.sha512.xz }}
+
+* <{{ release.url.zip }}>
+
+      SIZE: {{ release.size.zip }}
+      SHA1: {{ release.sha1.zip }}
+      SHA256: {{ release.sha256.zip }}
+      SHA512: {{ release.sha512.zip }}
+
+## Release Comment
+
+Many committers, developers, and users who provided bug reports helped us make this release.
+Thanks for their contributions.
diff --git a/ja/news/_posts/2026-03-11-ruby-3-4-9-released.md b/ja/news/_posts/2026-03-11-ruby-3-4-9-released.md
new file mode 100644
index 0000000000..3977164c1a
--- /dev/null
+++ b/ja/news/_posts/2026-03-11-ruby-3-4-9-released.md
@@ -0,0 +1,45 @@
+---
+layout: news_post
+title: "Ruby 3.4.9 リリース"
+author: nagachika
+translator: nagachika
+date: 2026-03-11 11:00:00 +0000
+lang: ja
+---
+
+Ruby 3.4.9 がリリースされました。
+
+このリリースには default gems zlib の [CVE-2026-27820 の対策を含むバージョン更新](https://www.ruby-lang.org/en/news/2026/03/05/buffer-overflow-zlib-cve-2026-27820/) が含まれています。
+その他にもいくつかの不具合修正が行なわれています。詳細は [GitHub releases](https://github.com/ruby/ruby/releases/tag/v3_4_9) を参照してください。
+
+このリリースは引き続きデフォルトのgemとして利用される場合のために行なわれているものです。明示的に zlib gem のバージョンを更新することをおすすめします。
+
+## ダウンロード
+
+{% assign release = site.data.releases | where: "version", "3.4.9" | first %}
+
+* <{{ release.url.gz }}>
+
+      SIZE: {{ release.size.gz }}
+      SHA1: {{ release.sha1.gz }}
+      SHA256: {{ release.sha256.gz }}
+      SHA512: {{ release.sha512.gz }}
+
+* <{{ release.url.xz }}>
+
+      SIZE: {{ release.size.xz }}
+      SHA1: {{ release.sha1.xz }}
+      SHA256: {{ release.sha256.xz }}
+      SHA512: {{ release.sha512.xz }}
+
+* <{{ release.url.zip }}>
+
+      SIZE: {{ release.size.zip }}
+      SHA1: {{ release.sha1.zip }}
+      SHA256: {{ release.sha256.zip }}
+      SHA512: {{ release.sha512.zip }}
+
+## リリースコメント
+
+Ruby 開発者の皆様、バグや脆弱性を報告してくれたユーザーの皆様のご協力により本リリースは行われています。
+皆様のご協力に感謝します。