Media endpoint has no path sanitization - authenticated arbitrary file read from GitHub repos #396

Summary

The media endpoint (packages/outstatic/src/app/api/media/index.ts) has zero sanitization on mediaPath. In legacy mode, mediaPath is interpolated into https://raw.githubusercontent.com/${mediaPath} and fetched server-side with the user GitHub OAuth token.

Vulnerability

An authenticated user can craft arbitrary paths to read files from any GitHub repository their token has access to, including private repos. For example: /api/outstatic/media/private-org/private-repo/main/secrets.env

This is distinct from GHSA-7jvc-9xq8-frff (REST proxy token leak to non-GitHub origins). That advisory covers the REST proxy. This finding covers the media endpoint allowing arbitrary repo path traversal.

Impact

Authenticated arbitrary file read from GitHub repositories, including private repos the user token can access.

Fix

Validate mediaPath against the configured repo owner/slug. Reject paths containing .. or not matching expected repo.