Multiple heap-based buffer overflow vulnerabilities exist in the fstReaderIterBlocks2 fstWritex len functionality of GTKWave 3.3.115. A specially crafted .fst file can lead to memory corruption. A victim would need to open a malicious file to trigger these vulnerabilities.This vulnerability concerns the handling of `len` in `fstWritex` when `beg_time` does not match the start of the time table.