libImaging/FliDecode.c in Pillow before 6.2.2 has an FLI buffer overflow.
https://www.debian.org/security/2020/dsa-4631
https://usn.ubuntu.com/4272-1/
https://pillow.readthedocs.io/en/stable/releasenotes/6.2.2.html
https://github.com/python-pillow/Pillow/commit/a09acd0decd8a87ccce939d5ff65dab59e7d365b