`auth.TokenForHost` violates GitHub host security boundary when sourcing authentication token within a codespace

Summary

A security vulnerability has been identified in go-gh that could leak authentication tokens intended for GitHub hosts to non-GitHub hosts when within a codespace.

Details

go-gh sources authentication tokens from different environment variables depending on the host involved:

• GITHUB_TOKEN, GH_TOKEN for GitHub.com and ghe.com
• GITHUB_ENTERPRISE_TOKEN, GH_ENTERPRISE_TOKEN for GitHub Enterprise Server

Prior to 2.11.1, auth.TokenForHost could source a token from the GITHUB_TOKEN environment variable for a host other than GitHub.com or ghe.com when within a codespace.

In 2.11.1, auth.TokenForHost will only source a token from the GITHUB_TOKEN environment variable for GitHub.com or ghe.com hosts.

Impact

Successful exploitation could send authentication token to an unintended host.

Remediation and mitigation

1. Upgrade go-gh to 2.11.1
2. Advise extension users to regenerate authentication tokens:
   • Personal access tokens
   • GitHub CLI OAuth app
3. Advise extension users to review their personal security log and any relevant audit logs for actions associated with their account or enterprise