Cursor urges credential resets after malicious Claude Code marketplace update

Code editor Cursor is urging developers who installed malicious Claude Code extension packages from its marketplace to clean affected machines and rotate accessible credentials and sessions from a trusted system. Removing the extension alone may leave persistent components running, the company warns. The affected packages are Anthropic.claude-code versions 2.1.312 and 2.1.313 for macOS and Windows. Cursor’s security notice places their availability between about 2:27 a.m. and 1:35 p.m. PT on Oct. 29, 2026. Cursor says Anthropic did not develop the malicious versions and reports no evidence that other versions or the official distribution were affected.