Malicious Claude Code extension in Cursor's marketplace attempts to install a persistent SSH backdoor
Cursor's security notice identifies a maliciously modified Claude Code extension in the Cursor VS Code Extension Marketplace; Cursor stated the versions were n…
Published on MyPrivateClaw
Oct 31, 2026, 12:42 AM UTC
Coverage date
Oct 30, 2026
Last updated
Oct 31, 2026, 12:42 AM UTC
News summary
A maliciously modified version of Anthropic's Claude Code extension, version 2.1.312 and 2.1.313 for Windows and MacOS, was available in the Cursor VS Code Extension Marketplace between about 2:27am PT and 1:35pm PT on October 29, 2026. The extension runs malicious code that attempts to install a persistent SSH backdoor. The incident affects only the Cursor marketplace distribution channel, not Anthropic's official channels. Cursor stated that these malicious versions of the Claude Code extension were not developed by Anthropic, and that there is no evidence that other versions of the extension or the official distribution are affected. The malicious extension appends the attacker's public key, labeled svc telemetry, to the SSH authorized keys file, attempts to enable the local SSH service, and opens a reverse SSH tunnel. Because enabling the local SSH service requires admin rights the…