diff --git a/package-lock.json b/package-lock.json
index dd762faabc..bcb41fcbfd 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
 	"name": "WordPress",
-	"version": "5.9.8",
+	"version": "5.9.9",
 	"lockfileVersion": 1,
 	"requires": true,
 	"dependencies": {
@@ -27314,4 +27314,4 @@
 			"dev": true
 		}
 	}
-}
+}
\ No newline at end of file
diff --git a/package.json b/package.json
index d3b6fc9160..125c00d280 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
 	"name": "WordPress",
-	"version": "5.9.8",
+	"version": "5.9.9",
 	"description": "WordPress is open source software you can use to create a beautiful website, blog, or app.",
 	"repository": {
 		"type": "svn",
@@ -176,4 +176,4 @@
 		"test:visual": "node ./tests/visual-regression/run-tests.js",
 		"wp-packages-update": "wp-scripts packages-update"
 	}
-}
+}
\ No newline at end of file
diff --git a/src/wp-admin/about.php b/src/wp-admin/about.php
index 0670197d14..a9281f0b3c 100644
--- a/src/wp-admin/about.php
+++ b/src/wp-admin/about.php
@@ -42,6 +42,26 @@ require_once ABSPATH . 'wp-admin/admin-header.php';
 		<div class="about__section changelog">
 			<div class="column">
 				<h2><?php _e( 'Maintenance and Security Releases' ); ?></h2>
+				<p>
+					<?php
+					printf(
+						/* translators: %s: WordPress version number. */
+						__( '<strong>Version %s</strong> addressed some security issues.' ),
+						'5.9.9'
+					);
+					?>
+					<?php
+					printf(
+						/* translators: %s: HelpHub URL. */
+						__( 'For more information, see <a href="%s">the release notes</a>.' ),
+						sprintf(
+							/* translators: %s: WordPress version. */
+							esc_url( __( 'https://wordpress.org/support/wordpress-version/version-%s/' ) ),
+							sanitize_title( '5.9.9' )
+						)
+					);
+					?>
+				</p>
 				<p>
 					<?php
 					printf(
diff --git a/src/wp-includes/version.php b/src/wp-includes/version.php
index 795d980041..a46515b1db 100644
--- a/src/wp-includes/version.php
+++ b/src/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.9.8-src';
+$wp_version = '5.9.9-src';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.