From ff545f4276d45aa8dc498e21c577d09b5b2307b6 Mon Sep 17 00:00:00 2001
From: Joe Mooring <joe.mooring@veriphor.com>
Date: Wed, 16 Feb 2022 10:56:23 -0800
Subject: [PATCH] markup/goldmark: Exclude event attributes from markdown
 render hook

Fixes #9511
---
 markup/goldmark/integration_test.go | 40 ++++++++++++++++++++++++++---
 markup/goldmark/render_hooks.go     |  3 +++
 2 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/markup/goldmark/integration_test.go b/markup/goldmark/integration_test.go
index 0f47f4ada..eda2ac423 100644
--- a/markup/goldmark/integration_test.go
+++ b/markup/goldmark/integration_test.go
@@ -20,6 +20,7 @@ import (
 	"github.com/gohugoio/hugo/hugolib"
 )
 
+// Issue 9463
 func TestAttributeExclusion(t *testing.T) {
 	t.Parallel()
 
@@ -55,9 +56,42 @@ foo
 	).Build()
 
 	b.AssertFileContent("public/p1/index.html", `
-<h2 class="a" id="heading">
-<blockquote class="b">
-<div class="highlight" id="c">
+		<h2 class="a" id="heading">
+		<blockquote class="b">
+		<div class="highlight" id="c">
+	`)
+}
+
+// Issue 9511
+func TestAttributeExclusionWithRenderHook(t *testing.T) {
+	t.Parallel()
+
+	files := `
+-- content/p1.md --
+---
+title: "p1"
+---
+## Heading {onclick="alert('renderhook')" data-foo="bar"}
+-- layouts/_default/single.html --
+{{ .Content }}
+-- layouts/_default/_markup/render-heading.html --
+<h{{ .Level }}
+  {{- range $k, $v := .Attributes -}}
+    {{- printf " %s=%q" $k $v | safeHTMLAttr -}}
+  {{- end -}}
+>{{ .Text | safeHTML }}</h{{ .Level }}>
+`
+
+	b := hugolib.NewIntegrationTestBuilder(
+		hugolib.IntegrationTestConfig{
+			T:           t,
+			TxtarString: files,
+			NeedsOsFS:   false,
+		},
+	).Build()
+
+	b.AssertFileContent("public/p1/index.html", `
+		<h2 data-foo="bar" id="heading">Heading</h2>
 	`)
 }
 
diff --git a/markup/goldmark/render_hooks.go b/markup/goldmark/render_hooks.go
index 5c600204c..1862c2125 100644
--- a/markup/goldmark/render_hooks.go
+++ b/markup/goldmark/render_hooks.go
@@ -57,6 +57,9 @@ func (a *attributesHolder) Attributes() map[string]string {
 	a.attributesInit.Do(func() {
 		a.attributes = make(map[string]string)
 		for _, attr := range a.astAttributes {
+			if strings.HasPrefix(string(attr.Name), "on") {
+				continue
+			}
 			a.attributes[string(attr.Name)] = string(util.EscapeHTML(attr.Value.([]byte)))
 		}
 	})