Anthropic VS code extension on Cursor backdoored for nearly 12 hours
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An official Anthropic VS Code extension distributed through the Cursor marketplace was compromised in a supply-chain attack, potentially affecting up to 5,000 developers. The malicious version 2.1.313 attempted to install a persistent SSH backdoor by adding an attacker-controlled key and opening a reverse tunnel across Windows, macOS, and Linux systems. Although coding errors prevented some persistence mechanisms from functioning correctly, the malware successfully collected host information and cloud credentials to prioritize future targets. Cursor removed the compromised package and temporarily shut down its marketplace to rotate keys and audit access controls. Despite the severity of the incident, neither Anthropic nor Cursor has publicly warned customers or explained how attackers gained control of the verified account. Independent researchers confirmed that the malicious code was posted via Anthropic’s official distribution channel before being superseded by a safe update. Users who installed or updated the extension during the affected timeframe are advised to check for indicators of compromise.
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