In AdvanceCOMP 2.1, png_compress in pngex.cc in advpng has an integer overflow upon encountering an invalid PNG size, which results in an attempted memcpy to write into a buffer that is too small. (There is also a heap-based buffer over-read.)
Exploit prediction scoring system (EPSS) score
EPSS Score 0.003
EPSS Ranking 55.3%