Description
tarfile.extractall() with the 'data' or 'tar'
filter could be bypassed by a crafted archive where a hardlink
references a symlink stored at a deeper name than the hardlink itself.
The extraction fallback validated the symlink at it's archived location
but recreated it at the hardlink's shallower
path, letting a relative
target the filter judged contained escape the destination directory.
This allowed a malicious tar archive to create a symlink pointing
outside the destination, enabling out-of-destination file reads or
writes. This was an incomplete fix of CVE-2025-4330.
