Advisories for Npm/Opencode-Ai package

2026

OpenCode's Unauthenticated HTTP Server Allows Arbitrary Command Execution

OpenCode automatically starts an unauthenticated HTTP server that allows any local process—or any website via permissive CORS—to execute arbitrary shell commands with the user's privileges.

Malicious website can execute commands on the local system through XSS in the OpenCode web UI

A malicious website can abuse the server URL override feature of the OpenCode web UI to achieve cross-site scripting on http://localhost:4096. From there, it is possible to run arbitrary commands on the local system using the /pty/ endpoints provided by the OpenCode API.