[Cursor Hack Exposed: Fireworks Leaks Key, Hackers Infiltrate Plugin Store Through AI Training Records] Beating AI News reports that Cursor has released the results of its investigation into the Claude Code plugin malware attack. After two weeks of investigation, the company discovered that the source of the attack was its AI service provider, Fireworks. According to Cursor, Fireworks leaked an access key granted by Cursor. Hackers used this key to copy historical Coding Agent execution records stored in Cursor's shared storage. This data primarily came from user sessions in 2025 where privacy mode was not enabled, and was originally used for model training. More seriously, some of the API keys in the records were not anonymized. Hackers used these credentials to further intrude into some of Cursor's internal software services, obtaining archived non-production code, customer service emails, product usage data, some AI dialogue summaries, and credentials previously submitted by users to customer service. On October 29th, hackers used credentials stolen from Cursor to directly tamper with the extension store's cache, providing users with versions 2.1.312 and 2.1.313 of Claude Code, which contained an SSH backdoor. The malicious version existed for approximately 11 hours, and up to 5,000 users may have downloaded it. The upstream plugin marketplace Open VSX was not tampered with, and the official Anthropic version was unaffected. Cursor disclosed that the leaked Coding Agent runtime records affected less than 0.05% of users, with less than 0.01% of users exposing their API credentials. Sessions with privacy mode enabled, customer code repositories, and production systems were not affected by the attack. Cursor stated that the last detected hacking activity was on November 1st, when it was successfully intercepted. The company has notified affected users to completely stop using Fireworks for inference requests, revoked their data access permissions, and rotated internal credentials and redeployed production infrastructure. [Original Link]