diff --git a/Gemfile b/Gemfile
index 9e29c04fca3..035c86efff3 100644
--- a/Gemfile
+++ b/Gemfile
@@ -146,8 +146,8 @@ gem 'rdoc', '~> 4.2'
 gem 'org-ruby', '~> 0.9.12'
 gem 'creole', '~> 0.5.0'
 gem 'wikicloth', '0.8.1'
-gem 'asciidoctor', '~> 1.5.2'
-gem 'asciidoctor-plantuml', '0.0.7'
+gem 'asciidoctor', '~> 1.5.6'
+gem 'asciidoctor-plantuml', '0.0.8'
 gem 'rouge', '~> 2.0'
 gem 'truncato', '~> 0.7.9'
 gem 'bootstrap_form', '~> 2.7.0'
diff --git a/Gemfile.lock b/Gemfile.lock
index d50b3b1857a..7d8b22359b2 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -56,8 +56,8 @@ GEM
       faraday_middleware (~> 0.9)
       faraday_middleware-multi_json (~> 0.0)
       oauth2 (~> 1.0)
-    asciidoctor (1.5.3)
-    asciidoctor-plantuml (0.0.7)
+    asciidoctor (1.5.6.2)
+    asciidoctor-plantuml (0.0.8)
       asciidoctor (~> 1.5)
     asset_sync (2.2.0)
       activemodel (>= 4.1.0)
@@ -999,8 +999,8 @@ DEPENDENCIES
   akismet (~> 2.0)
   allocations (~> 1.0)
   asana (~> 0.6.0)
-  asciidoctor (~> 1.5.2)
-  asciidoctor-plantuml (= 0.0.7)
+  asciidoctor (~> 1.5.6)
+  asciidoctor-plantuml (= 0.0.8)
   asset_sync (~> 2.2.0)
   attr_encrypted (~> 3.0.0)
   awesome_print (~> 1.2.0)
diff --git a/changelogs/unreleased/44712-update-asciidoctor-from-1-5-3-to-1-5-6-2.yml b/changelogs/unreleased/44712-update-asciidoctor-from-1-5-3-to-1-5-6-2.yml
new file mode 100644
index 00000000000..bdfed89d2ea
--- /dev/null
+++ b/changelogs/unreleased/44712-update-asciidoctor-from-1-5-3-to-1-5-6-2.yml
@@ -0,0 +1,5 @@
+---
+title: Update asciidoctor-plantuml to 0.0.8
+merge_request: 18022
+author: Takuya Noguchi
+type: performance
diff --git a/spec/lib/gitlab/asciidoc_spec.rb b/spec/lib/gitlab/asciidoc_spec.rb
index 2a0e19ae796..e1782cff81a 100644
--- a/spec/lib/gitlab/asciidoc_spec.rb
+++ b/spec/lib/gitlab/asciidoc_spec.rb
@@ -48,7 +48,7 @@ module Gitlab
           },
           'images' => {
             input: 'image:https://localhost.com/image.png[Alt text" onerror="alert(7)]',
-            output: "<img src=\"https://localhost.com/image.png\" alt=\"Alt text\">"
+            output: "<div>\n<p><span><img src=\"https://localhost.com/image.png\" alt='Alt text\" onerror=\"alert(7)'></span></p>\n</div>"
           },
           'pre' => {
             input: '```mypre"><script>alert(3)</script>',