Anthropic VS Code extension distributed malicious update

An official extension for Anthropic’s Claude model, hosted on the Cursor editor marketplace, was compromised by a malicious update. The malicious version, labeled 2.1.313, was distributed via Anthropic’s official account, allowing it to reach users through the platform’s automatic update system.

Security researchers identified the incident as a supply-chain attack that persisted for approximately 12 hours before a patched version, 2.1.314, was released. Industry experts estimate that as many as 5,000 developer machines may have been affected by the breach. The primary objective of the malicious code appears to have been the unauthorized acquisition of cloud service credentials.

Neither Anthropic nor Cursor have provided a public explanation regarding how attackers gained access to the official distribution channel. The incident underscores ongoing vulnerabilities in software development supply chains where automated update mechanisms can be leveraged to distribute malicious payloads.