diff --git a/modules/markup/markdown/markdown_test.go b/modules/markup/markdown/markdown_test.go
index 4eb01bcc2da52..593a5dce5c1e1 100644
--- a/modules/markup/markdown/markdown_test.go
+++ b/modules/markup/markdown/markdown_test.go
@@ -17,6 +17,7 @@ import (
 	"code.gitea.io/gitea/modules/util"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 const (
@@ -547,3 +548,45 @@ func TestMarkdownLink(t *testing.T) {
 <a href="#user-content-foo" rel="nofollow">link3</a></p>
 `, string(result))
 }
+
+func TestToCWithHTML(t *testing.T) {
+	defer test.MockVariableValue(&markup.RenderBehaviorForTesting.DisableAdditionalAttributes, true)()
+
+	t1 := `tag <a href="link">link</a> and <b>Bold</b>`
+	t2 := "code block `<a>`"
+	t3 := "markdown **bold**"
+	input := `---
+include_toc: true
+---
+
+# ` + t1 + `
+# ` + t2 + `
+# ` + t3 + `
+`
+
+	resultHTML, err := markdown.RenderString(markup.NewTestRenderContext(), input)
+	assert.NoError(t, err)
+	result := string(resultHTML)
+
+	pos1, pos2 := strings.Index(result, `<ul>`), strings.Index(result, `</ul>`)
+	require.Positive(t, pos1)
+	require.Positive(t, pos2)
+	partToc, partContent := result[pos1:pos2+5], result[pos2+5:]
+	pos3 := strings.Index(partContent, "<h1")
+	require.Positive(t, pos3)
+	partContent = partContent[pos3:]
+
+	assert.Equal(t, `<ul>
+<li>
+<a href="#user-content-user-content-tag-a-hreflinklinka-and-bboldb" rel="nofollow">tag link and Bold</a></li>
+<li>
+<a href="#user-content-user-content-code-block-a" rel="nofollow">code block </a></li>
+<li>
+<a href="#user-content-user-content-markdown-bold" rel="nofollow">markdown bold</a></li>
+</ul>`, partToc)
+
+	assert.Equal(t, `<h1 id="user-content-tag-a-hreflinklinka-and-bboldb">tag <a href="/link" rel="nofollow">link</a> and <b>Bold</b></h1>
+<h1 id="user-content-code-block-a">code block <code>&lt;a&gt;</code></h1>
+<h1 id="user-content-markdown-bold">markdown <strong>bold</strong></h1>
+`, partContent)
+}
diff --git a/modules/markup/markdown/transform_heading.go b/modules/markup/markdown/transform_heading.go
index a229a7b1a4d20..010c0ef2cbc69 100644
--- a/modules/markup/markdown/transform_heading.go
+++ b/modules/markup/markdown/transform_heading.go
@@ -9,6 +9,7 @@ import (
 	"code.gitea.io/gitea/modules/markup"
 	"code.gitea.io/gitea/modules/util"
 
+	"github.com/microcosm-cc/bluemonday"
 	"github.com/yuin/goldmark/ast"
 	"github.com/yuin/goldmark/text"
 )
@@ -20,6 +21,7 @@ func (g *ASTTransformer) transformHeading(_ *markup.RenderContext, v *ast.Headin
 		}
 	}
 	txt := v.Text(reader.Source()) //nolint:staticcheck // Text is deprecated
+	txt = bluemonday.StrictPolicy().SanitizeBytes(txt)
 	header := Header{
 		Text:  util.UnsafeBytesToString(txt),
 		Level: v.Level,