$zip is failing to extract files if the filename in the central dir is different than in the local header
This is due to how libzip handles this issue, so either way it would not be possible for mIRC to change it.
But $zip should filter filenames containing ..
Ye gods. Thanks for spotting this! I never considered that the zip format would allow ".." in path names. I am not sure how best to handle this though. Should mIRC ignore specific files that contain ".." in their path but extract all others? Or should it assume that any zip file that contains ".." in a path name is malicious? I would opt to fail the entire zip file since, if it contains "..", it was most likely intended to be malicious and may contain other malicious files. This change will be in the next beta.