1 files changed, 15 insertions, 2 deletions
diff --git a/lib/banzai/filter/inline_diff_filter.rb b/lib/banzai/filter/inline_diff_filter.rb
index e47ff15e7b7..2a43540934c 100644
--- a/lib/banzai/filter/inline_diff_filter.rb
+++ b/lib/banzai/filter/inline_diff_filter.rb
@@ -6,6 +6,14 @@ module Banzai
     class InlineDiffFilter < HTML::Pipeline::Filter
       IGNORED_ANCESTOR_TAGS = %w(pre code tt).to_set
 
+      INLINE_DIFF_DELETION_UNTRUSTED = '(?:\[\-(.*?)\-\]|\{\-(.*?)\-\})'
+      INLINE_DIFF_DELETION_UNTRUSTED_REGEX =
+        Gitlab::UntrustedRegexp.new(INLINE_DIFF_DELETION_UNTRUSTED, multiline: false)
+
+      INLINE_DIFF_ADDITION_UNTRUSTED = '(?:\[\+(.*?)\+\]|\{\+(.*?)\+\})'
+      INLINE_DIFF_ADDITION_UNTRUSTED_REGEX =
+        Gitlab::UntrustedRegexp.new(INLINE_DIFF_ADDITION_UNTRUSTED, multiline: false)
+
       def call
         doc.xpath('descendant-or-self::text()').each do |node|
           next if has_ancestor?(node, IGNORED_ANCESTOR_TAGS)
@@ -21,8 +29,13 @@ module Banzai
       end
 
       def inline_diff_filter(text)
-        html_content = text.gsub(/(?:\[\-(.*?)\-\]|\{\-(.*?)\-\})/, '<span class="idiff left right deletion">\1\2</span>')
-        html_content.gsub(/(?:\[\+(.*?)\+\]|\{\+(.*?)\+\})/, '<span class="idiff left right addition">\1\2</span>')
+        html_content = INLINE_DIFF_DELETION_UNTRUSTED_REGEX.replace_gsub(text) do |match|
+          %(<span class="idiff left right deletion">#{match[1]}#{match[2]}</span>)
+        end
+
+        INLINE_DIFF_ADDITION_UNTRUSTED_REGEX.replace_gsub(html_content) do |match|
+          %(<span class="idiff left right addition">#{match[1]}#{match[2]}</span>)
+        end
       end
     end
   end