CHMLib through 2bef8d0, as used in SumatraPDF and other products, has a chm_lib.c _chm_decompress_block integer overflow. There is a resultant heap-based buffer overflow in _chm_fetch_bytes.Referenceshttps://drive.google.com/file/d/1XpulFyCGlq7Szzg5RsH-eRwZ6OyuSozl/view?usp=sharinghttps://drive.google.com/file/d/1wq51px42eoJz2VQ1Qu9ObPVQVom9T9H_/view?usp=sharinghttps://github.com/jedwing/CHMLib/blob/2bef8d063ec7d88a8de6fd9f0513ea42ac0fa21f/src/chm_lib.c#L1386https://github.com/sumatrapdfreader/sumatrapdf/commit/08179946a745cf1605e4b9670942ec1a6e1f4c5d
