Integer overflow in the rwpng_read_image24_libpng function in rwpng.c in pngquant 2.7.0 allows remote attackers to have unspecified impact via a crafted PNG file, which triggers a buffer overflow.
https://lists.debian.org/debian-lts-announce/2020/06/msg00028.html
https://github.com/pornel/pngquant/commit/b7c217680cda02dddced245d237ebe8c383be285