lakeFS vulnerable to path traversal in local block adapter allow cross-namespace and sibling directory access

Summary

lakeFS is an open-source tool that transforms object storage into a Git-like repositories. Prior to 1.77.0, the local block adapter (pkg/block/local/adapter.go) allows authenticated users to read and write files outside their designated storage boundaries. The verifyRelPath function used strings.HasPrefix() to verify that requested paths fall within the configured storage directory. This check was insufficient because it validated only the path prefix without requiring a path separator, allowing access to sibling directories with similar names. Also, the adapter verified that resolved paths stayed within the adapter's base path, but did not verify that object identifiers stayed within their designated storage namespace. This allowed attackers to use path traversal sequences in the object identifier to access files in other namespaces. Fixed in version v1.77.0.