Cursor says up to 5,000 users affected by tampered Claude Code extension


FILE PHOTO: Claude logo and a keyboard in this illustration taken October 19, 2026. REUTERS/Dado Ruvic/Illustration/File Photo

Oct 30 (Reuters) - Cursor, ⁠the coding-tool company owned by SpaceX, said ⁠on Friday that a maliciously modified version ‌of Anthropic’s Claude Code extension was available on its Cursor VS Code extension marketplace on Thursday, affecting up ​to 5,000 users.

Here are some details:

• ⁠Cursor said the ⁠extension was not developed by Anthropic and the ⁠maliciously modified ‌extension was live on the marketplace from about 2:27 a.m. PT to ⁠1:35 p.m. PT on Thursday

• The extension ​attempted to ‌collect host and user information such as ⁠hostname, username, ​operating system and public IP address

• It also attempted to set up remote access for the ⁠attacker; Cursor said a key ​step would have failed on most machines because it requires administrator rights

• Upon detection, Cursor removed ⁠the malicious version and blocked its distribution and shut down the marketplace as a precaution

• The company then rebuilt the marketplace and brought ​it back online, it said

• ⁠Cursor said the incident did not impact other ​extensions on its marketplace

• Anthropic ‌did not immediately respond to ​a request for comment

(Reporting by Shubham Kalia in Bengaluru; Editing by Mrigank Dhaniwala)

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