Tampered Claude Code add-on in Cursor’s store had a backdoor
Versions 2.1.312 and 2.1.313 tried to give an unknown attacker remote access to developers’ computers. Cursor pulled them after about 11 hours, and Anthropic says it never built or published them.
For about 11 hours on October 29, Cursor’s extension store offered a tampered copy of Anthropic’s Claude Code extension. Cursor says the bad builds added an attacker’s SSH key, tried to open remote access and sent out details about each computer. Cursor shut the store down and rebuilt it, and it says removing the extension may not be enough.