Significantly, it's not just libjpeg but every format supported by Pillow (http://pillow.readthedocs.io/en/3.4.x/handbook/image-file-fo...) — many of those vulnerabilities have historically been in obscure formats where the implementation has had far less attention than the mainline JPEG or PNG support.

Yep, I remember multiple smaller art-centric sites getting hit in a wave by an ImageMagick RCE vulnerability. Database dumps, full source leaks, the works. Unsure whether it was the one you linked; it seems more recent than I thought.