Leptonica before 1.80.0 allows a heap-based buffer over-read in pixFewColorsOctcubeQuantMixed in colorquant1.c.
https://security.gentoo.org/glsa/202107-53
https://lists.debian.org/debian-lts-announce/2021/03/msg00037.html
https://github.com/DanBloomberg/leptonica/compare/1.79.0...1.80.0
https://github.com/DanBloomberg/leptonica/commit/5ee24b398bb67666f6d173763eaaedd9c36fb1e5