diff --git a/app/models/attachment.rb b/app/models/attachment.rb
index 74669f569..a9d15d946 100644
--- a/app/models/attachment.rb
+++ b/app/models/attachment.rb
@@ -24,6 +24,7 @@ class Attachment < ActiveRecord::Base
   validates_presence_of :filename, :author
   validates_length_of :filename, :maximum => 255
   validates_length_of :disk_filename, :maximum => 255
+  validates_length_of :description, :maximum => 255, :allow_blank => true
   validate :validate_max_file_size
 
   acts_as_event :title => :filename,
diff --git a/app/views/attachments/_form.html.erb b/app/views/attachments/_form.html.erb
index 7eea17bb7..dd55fa3f1 100644
--- a/app/views/attachments/_form.html.erb
+++ b/app/views/attachments/_form.html.erb
@@ -10,7 +10,7 @@
   <span>
     <%= file_field_tag 'attachments[1][file]', :size => 30, :id => nil, :class => 'file',
           :onchange => "checkFileSize(this, #{Setting.attachment_max_size.to_i.kilobytes}, '#{escape_javascript(l(:error_attachment_too_big, :max_size => number_to_human_size(Setting.attachment_max_size.to_i.kilobytes)))}');"  -%>
-    <%= text_field_tag 'attachments[1][description]', '', :id => nil, :class => 'description', :placeholder => l(:label_optional_description) %>
+    <%= text_field_tag 'attachments[1][description]', '', :id => nil, :class => 'description', :maxlength => 255, :placeholder => l(:label_optional_description) %>
     <%= link_to_function(image_tag('delete.png'), 'removeFileField(this)', :title => (l(:button_delete))) %>
   </span>
 </span>
diff --git a/doc/CHANGELOG b/doc/CHANGELOG
index eb606b059..41d09614f 100644
--- a/doc/CHANGELOG
+++ b/doc/CHANGELOG
@@ -8,6 +8,7 @@ http://www.redmine.org/
 
 * Defect #11192: Make repository identifier accept underscores
 * Defect #11307: Can't filter for negative numeric custom fields
+* Defect #11365: Attachment description length is not validated
 * Feature #11338: Exclude emails with auto-submitted => auto-generated
 * Patch #11328: Fix Japanese mistranslation for 'label_language_based'
 
diff --git a/test/functional/issues_controller_test.rb b/test/functional/issues_controller_test.rb
index e039468c2..9a842012a 100644
--- a/test/functional/issues_controller_test.rb
+++ b/test/functional/issues_controller_test.rb
@@ -1305,6 +1305,7 @@ class IssuesControllerTest < ActionController::TestCase
         :tag => 'input',
         :attributes => {:type => 'file', :name => 'attachments[1][file]'}
       }
+    assert_select 'input[name=?][maxlength=255]', 'attachments[1][description]'
   end
 
   def test_get_new_should_prefill_the_form_from_params
diff --git a/test/unit/attachment_test.rb b/test/unit/attachment_test.rb
index 9238a10c7..627c5c6fc 100644
--- a/test/unit/attachment_test.rb
+++ b/test/unit/attachment_test.rb
@@ -75,6 +75,12 @@ class AttachmentTest < ActiveSupport::TestCase
     end
   end
 
+  def test_description_length_should_be_validated
+    a = Attachment.new(:description => 'a' * 300)
+    assert !a.save
+    assert_not_nil a.errors[:description]
+  end
+
   def test_destroy
     a = Attachment.new(:container => Issue.find(1),
                        :file => uploaded_test_file("testfile.txt", "text/plain"),