Active Storage's default vips variant processor exposes an arbitrary file read that chains to RCE on stock Rails 7.x and 8.x, where the app serves back processed variants of user-supplied images. No authentication required in certain setups. Only vips is affected, Magick is not.
Patched in 7.2.3.2, 8.0.5.1, and 8.1.3.1, and the fix requires libvips 8.13+. Chain and PoC withheld while patches roll out.