Anthropic's official Claude VS Code extension on Cursor carried a backdoor for nearly 12 hours

Anthropic VS code extension on Cursor backdoored for nearly 12 hours

Anthropic's official Claude VS Code extension on the Cursor marketplace was backdoored. The malicious version 2.1.313 reached up to 5,000 users, security researchers say. It was distributed through Anthropic's official account, and Cursor auto-updates extensions by default. Anthropic pushed 2.1.314 hours later. As of the report, Anthropic had not warned customers, and neither company explained how the attacker took over the account.

Why it matters: A malicious extension shipped through Anthropic's official Cursor channel, and default auto-update put it on developer machines.