Article · AI translation
Thanks to IT Home reader 惊讶仙人 for the tip!
IT Home reported on November 14 that, on October 29 local time, Cursor announced that a malicious and unauthorized copy of the Anthropic Claude Code extension had appeared in the Cursor VS Code extension marketplace.
On November 13 local time, after a comprehensive investigation over the preceding two weeks, Cursor disclosed its findings on the security incident. The company said the vast majority of customers were unaffected and that at most 5,000 users were affected. It has contacted each affected customer directly and provided details relevant to them.
According to Cursor, prompts and code were unaffected for users who enabled privacy mode. Among users who did not use privacy mode, fewer than 0.05% had programming agent trace data exposed. Cursor has identified these users and notified each of them directly. If you have not received a notification, your data was not among those traces.
The company said it is learning from the incident and further improving Cursor's security.
IT Home provides a brief account of the incident:
Fireworks key leak: The attacker used a leaked Fireworks access key to steal some data from Cursor's shared storage bucket. Using a small number of unredacted credentials found there, affecting fewer than 0.01% of customers, the attacker gained access to some of Cursor's SaaS tools and accessed some non-production code repositories, customer support data, and some user credentials.
Detection and emergency response: After detecting unusual activity, Cursor immediately disabled the leaked key, rotated credentials, and cut off unauthorized access. It also shut down some internal and product services as a precaution and gradually restored them after confirming they were secure.
Malicious extension insertion: On October 29, the attacker used stolen internal credentials to insert a tampered version of the Anthropic Claude Code extension into the Cursor extension marketplace. Anthropic and Open VSX were not involved. The malicious version remained available for about 11 hours and affected at most 5,000 users. Cursor then removed the extension, temporarily took the marketplace offline, and worked with its cloud provider to shut down the attacker's server.
Customer notification and recommended action: On October 30, Cursor published a security notice, notified affected parties, and helped revoke and rotate leaked keys. Users who installed a malicious version (Anthropic.claude-code 2.1.312 or 2.1.313) need to follow the notice's instructions to investigate; uninstalling the extension alone does not fully eliminate the risk.
Incident contained: After blocking the final attack on November 1, Cursor confirmed that the incident was contained. It will continue to strengthen monitoring and defenses and will notify affected customers directly if there are further developments.