Security notice — malicious version of Anthropic.claude-code (2.1.313) identified in the Cursor Extension Marketplace

Cursor reported that a maliciously modified Anthropic.claude-code version 2.1.313 was available in its VS Code extension Marketplace between about 2:27am and 1:35pm PT, affecting at most 5,000 users; the extension attempted to install a persistent SSH backdoor, though the attacker server has since been taken offline. Cursor removed the version, shut down and rebuilt the marketplace, rotated keys, and published indicators of compromise plus macOS and Windows check and remediation scripts. Users who installed the version in that window should check for the svc-telemetry SSH key, remove persistence and tunnel processes, and rotate credentials from a trusted system.