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Escape image titles and alt text in Markdown #493

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Merged
djmb merged 2 commits into from
Sep 29, 2026
Merged

Escape image titles and alt text in Markdown #493

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8b4aac7
Escape image titles and alt text in Markdown
djmb Sep 29, 2026
824ba3d
Keep existing entities in image titles and alt text, and test URL esc…
djmb Sep 29, 2026
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1 change: 1 addition & 0 deletions lib/markdown_renderer.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,7 @@ def header(text, header_level)
end

def image(url, title, alt_text)
url, title, alt_text = [ url, title, alt_text ].map { ERB::Util.html_escape_once(it) }
%(<a title="#{title}" data-action="lightbox#open:prevent" data-lightbox-target="image" data-lightbox-url-value="#{url}?disposition=attachment" href="#{url}"><img src="#{url}" alt="#{alt_text}"></a>)
end

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10 changes: 10 additions & 0 deletions test/lib/markdown_renderer_test.rb
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Expand Up @@ -8,4 +8,14 @@ class MarkdownRendererTest < ActiveSupport::TestCase
assert_includes content, "id='duplicated-header'"
assert_includes content, "id='duplicated-header-2'"
end

test "it escapes image attributes" do
markdown = MarkdownRenderer.build
content = markdown.render(%(![a "b" &amp; c](/image.png?a=1&b=2 "x" data-x="y")))

assert_includes content, %(title="x&quot; data-x=&quot;y")
assert_includes content, %(alt="a &quot;b&quot; &amp; c")
assert_includes content, %(href="/image.png?a=1&amp;b=2")
assert_empty Nokogiri::HTML5.fragment(content).css("[data-x]")
end
end
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