An issue was discovered in Pillow before 8.2.0. For FLI data, FliDecode did not properly check that the block advance was non-zero, potentially leading to an infinite loop on load.
github.com/python-pillow/Pillow/commit/bb6c11fb889e6c11b0ee122b828132ee763b5856
github.com/python-pillow/Pillow/pull/5377
lists.debian.org/debian-lts-announce/2021/07/msg00018.html
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MQHA5HAIBOYI3R6HDWCLAGFTIQP767FL/
pillow.readthedocs.io/en/stable/releasenotes/8.2.0.html#cve-2021-28676-fix-fli-dos
security.gentoo.org/glsa/202107-33