Arcane: Authenticated Arbitrary Host File Read via Docker Compose Include Directives in Arcane

Arcane is an interface for managing Docker containers, images, networks, and volumes. Prior to 1.19.4, 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. This vulnerability is fixed in 1.19.4.