Vulnerability Instance

Local File Inclusion in Rack::Static
## Summary

`Rack::Static` can serve files under the specified `root:` even if `urls:` are provided, which may expose other files under the specified `root:` unexpectedly.

## Details

The vulnerability occurs because `Rack::Static` does not properly sanitize user-supplied paths before serving files. Specifically, encoded path traversal sequences are not correctly validated, allowing attackers to access files outside the designated static file directory.

## Impact

By exploiting this vulnerability, an attacker can gain access to all files under the specified `root:` directory, provided they are able to determine then path of the file.

## Mitigation

- Update to the latest version of Rack, or
- Remove usage of `Rack::Static`, or
- Ensure that `root:` points at a directory path which only contains files which should be accessed publicly.

It is likely that a CDN or similar static file server would also mitigate the issue.