Anthropic's Claude extension on Cursor was backdoored for about 12 hours

An official VS Code extension for Anthropic's Claude, listed on Cursor's marketplace, was compromised in a supply-chain attack. The malicious version 2.1.313 was pushed through Anthropic's verified account and reached at most 5,000 users before version 2.1.314 replaced it hours later. Neither company has explained how attackers gained access, and Anthropic had not yet warned customers.