See how chmlib compares to other vendors in security performance
CHMLib through 2bef8d0, as used in SumatraPDF and other products, has a chmlib.c chmdecompressblock integer overflow. There is a resultant heap-based buffer overflow in chmfetchbytes.
chmlib before 0.39 allows user-assisted remote attackers to execute arbitrary code via a crafted page block length in a CHM file, which triggers memory corruption.