CVE-2026-47179: Arcane Has an Authenticated Arbitrary Host File Read via Docker Compose Include Directives

ProjectService.GetProjectFileContent returns the contents of any Docker Compose include directive declared in a project’s compose file before any path-traversal validation runs. Because ProjectService.CreateProject writes attacker-supplied compose content to disk without validating include paths, an authenticated user can create a project whose compose file declares include: ['../../../../etc/passwd'], then read the include via the project file API. The result is arbitrary read of any file readable by the Arcane backend process, including /app/data/arcane.db (the SQLite database containing every user’s password hash and API key), enabling escalation to admin and, via Arcane’s Docker control plane, RCE on the host.