GHSA-gpfj-4j6g-c4w9

### Impact

A self Cross-Site Scripting vulnerability exists in the @github/paste-markdown library. If the clipboard data contains the string `<table>`, a **div** is dynamically created, and the clipboard content is copied into its **innerHTML** property without any sanitization, resulting in improper execution of JavaScript in the browser of the victim (the user who pasted the code). Users directed to copy text from a malicious website and paste it into pages that utilize this library are affected.

The following @github/paste-markdown code snippet is triggered when the user pastes something and the browser's clipboard data contains an entry whose content-type is **text/HTML**.

```typescript function generateText(transfer: DataTransfer): string | undefined { if (Array.from(transfer.types).indexOf('text/html') === -1) return

let html = transfer.getData('text/html') if (!/<table/i.test(html)) return

html = html.replace(/<meta.*?>/, '')

const el = document.createElement('div') el.innerHTML = html const tables = el.querySelectorAll('table')

for (const table of tables) { if (table.closest('[data-paste-markdown-skip]')) { table.replaceWith(new Text(table.textContent || '')) } const formattedTable = tableMarkdown(table) table.replaceWith(new Text(formattedTable)) }

return el.innerHTML } ```

### Patches A security patch was released in [version 0.3.4](https://github.com/github/paste-markdown/releases/tag/v0.3.4).

### Workarounds A Content Security Policy that prevents `unsafe-inline` helps reduce the likelihood of this vulnerability being exploited in modern browsers.

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