Backdoored Anthropic VS Code extension distributed via Cursor marketplace

Key points

• Malicious version 2.1.313 was posted to Anthropic's official Cursor account, with at most 5,000 users affected, according to Cursor.
• The code reportedly attempted a persistent SSH backdoor and reverse tunnel, though bugs limited it in some Windows and macOS cases.
• Anyone who installed or updated the extension from Cursor between 5:27 am and 4:35 pm ET Thursday should consider themselves affected.
• Anthropic has not publicly warned customers, and neither company has explained how the attackers gained control of the account.

Why it matters for marketers: Teams using AI coding tools should audit installed extensions and auto-update settings now, since Cursor enables extension auto-updates by default.