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fix: sanitize HTML in MarkdownRenderer during SSR #1247

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Merged
RUKAYAT-CODER merged 2 commits into from
Aug 26, 2026
+80 −2
Merged

fix: sanitize HTML in MarkdownRenderer during SSR #1247

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f2e2302
fix: sanitize HTML in MarkdownRenderer during SSR
jotel-dev Aug 25, 2026
af837be
Merge branch 'main' into main
Benedict315 Aug 26, 2026
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81 changes: 80 additions & 1 deletion src/components/shared/MarkdownRenderer.test.ts
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
import { describe, it, expect } from 'vitest';
import { markdownToHtml, clusterMarkdownLines } from './MarkdownRenderer';
import { markdownToHtml } from './MarkdownRenderer';
import DOMPurify from 'dompurify';

// Tests cover the pure markdownToHtml function (no DOM/React needed).

Expand Down Expand Up @@ -194,6 +195,84 @@ describe('markdownToHtml', () => {
expect(html).toContain('<th>A</th>');
expect(html).toContain('<td>1</td>');
});

// ── DOMPurify sanitization ───────────────────────────────────────────────────

it('sanitizes malicious HTML with DOMPurify using component config', () => {
const md = '<img src="x" onerror="alert(1)">';
const raw = markdownToHtml(md);
const sanitized = DOMPurify.sanitize(raw, {
ALLOWED_TAGS: [
'h1',
'h2',
'h3',
'h4',
'h5',
'h6',
'p',
'br',
'strong',
'em',
'del',
'code',
'pre',
'ul',
'ol',
'li',
'blockquote',
'hr',
'a',
'img',
'table',
'thead',
'tbody',
'tr',
'th',
'td',
'input',
],
ALLOWED_ATTR: ['href', 'src', 'alt', 'class', 'target', 'rel', 'type', 'checked', 'disabled'],
});
expect(sanitized).not.toContain('onerror');
});

it('sanitizes script tags with DOMPurify using component config', () => {
const md = '<script>alert("XSS")</script>';
const raw = markdownToHtml(md);
const sanitized = DOMPurify.sanitize(raw, {
ALLOWED_TAGS: [
'h1',
'h2',
'h3',
'h4',
'h5',
'h6',
'p',
'br',
'strong',
'em',
'del',
'code',
'pre',
'ul',
'ol',
'li',
'blockquote',
'hr',
'a',
'img',
'table',
'thead',
'tbody',
'tr',
'th',
'td',
'input',
],
ALLOWED_ATTR: ['href', 'src', 'alt', 'class', 'target', 'rel', 'type', 'checked', 'disabled'],
});
expect(sanitized).not.toContain('<script>');
});
});

// ── Clustering algorithm ───────────────────────────────────────────────────
Expand Down
1 change: 0 additions & 1 deletion src/components/shared/MarkdownRenderer.tsx
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Original file line number Diff line number Diff line change
Expand Up @@ -285,7 +285,6 @@ export interface MarkdownRendererProps {
export function MarkdownRenderer({ content, className = '' }: MarkdownRendererProps) {
const sanitizedHtml = useMemo(() => {
const raw = markdownToHtml(content);
if (typeof window === 'undefined') return raw;
return DOMPurify.sanitize(raw, {
ALLOWED_TAGS: [
'h1',
Expand Down
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