Trojanized Claude Code Extensions Put Cursor and Open VSX Users at Risk

New reporting describes a persistent SSH backdoor in a tampered Claude Code extension, including an added SSH key, recurring tunnel, host reconnaissance, and potential credential inventory. Cursor says up to 5,000 users may have been affected and removed its extension; successful access remains unclear. A separate report identifies malicious Claude Code 2.1.313 on Open VSX, but distribution scope and its relationship to the Cursor incident require careful verification; this is a developer-tool supply-chain incident, not an established agent-caused production failure.