Source: stepsecurity.io
On October 29, 2026, a malicious version (2.1.313) of the Claude Code VS Code extension was published to Cursor's extension marketplace. The trojanized extension reached up to 5,000 Cursor users during an 11-hour exposure window. Upon loading, the extension planted an attacker-controlled SSH key on the victim machine and established persistence mechanisms tailored to each operating system. It also opened a reverse SSH tunnel back to attacker-controlled infrastructure, enabling persistent remote access. Additionally, the malware collected host reconnaissance data and transmitted it over unencrypted plain HTTP. The attack represents a supply chain compromise targeting software developers using the Cursor IDE environment. The incident highlights risks associated with third-party extension marketplaces and the potential for developer machine compromise via IDE plugins.
