Cursor Closes Its Store After Trapped Claude Code Extension

Cursor temporarily cut off access to its extension marketplace after detecting a compromised version of Claude Code. This variant, which remained online for about eleven hours on Thursday, may have affected up to 5,000 users, according to the company. The publisher states that it neutralized the malware with partners before reopening the store and assures that no other extensions were impacted. Anthropic is not involved in this development.

Store taken offline and then restored after neutralization, limited scope according to Cursor

After discovering the malicious version of the Claude Code extension, Cursor first removed the extension from the marketplace and then took its entire extension marketplace offline. The company specifies that it collaborated with vendors to eliminate the malware and only restored access after confirming the absence of risk. Cursor claims that no other extensions were affected by this incident.

The payload targeted system information and remote access

The compromised variant of Claude Code sought to retrieve data such as the hostname, username, operating system, and public IP address. It also attempted to install remote access for the attacker. According to Cursor, this remote access attempt likely failed on most machines, as it required administrative rights.

An eleven-hour window on Thursday and up to 5,000 affected users

The modified version of the Claude Code extension was available on Cursor's VS Code extension marketplace for about eleven hours on Thursday. According to Cursor, up to 5,000 users may have been exposed to this extension. Anthropic played no role in the development of this version.