Source: socket.dev
Cursor confirmed a malicious Claude Code extension version 2.1.313 was available through its marketplace on October 29, potentially affecting up to 5,000 users. The extension contained code to add SSH authorized keys, establish a reverse SSH tunnel, and install persistence mechanisms. Socket's investigation found no evidence that this version was published to Open VSX or npm registries, challenging initial reports attributing distribution to those channels. The original report by OpenSourceMalware has since been revised, removing Open VSX as the identified distribution channel. Screenshot evidence in the original report showed suspicious discrepancies, with file sizes matching version 2.1.314 rather than 2.1.313. Cursor responded by removing the extension, rebuilding its marketplace with rotated keys, and working with hosting providers to take down the attacker's server. Cursor published remediation guidance including package hashes and indicators of compromise for the malicious macOS and Windows packages.
