Ruby on Rails Patches Critical Vulnerability

Rapid7 analyzes KindaRails2Shell (CVE-2026-66066), a Ruby on Rails Active Storage vulnerability that can allow attackers to abuse libvips and crafted MAT/HDF5 uploads to read arbitrary files from the server. The analysis explains the direct-upload type confusion, the HDF5 external storage primitive, how Rails signing material can be recovered, and how the chain can lead to remote code execution.