CVE-2025-4138

A flaw was found in the Python tarfile module. This vulnerability allows attackers to bypass extraction filters, enabling symlink targets to escape the destination directory and allowing unauthorized modification of file metadata via the use of TarFile.extract() or TarFile.extractall() with the filter= parameter set to "data" or "tar".

Versions of python36:3.6/python36 as shipped with Red Hat Enterprise Linux 8 are marked as 'Not affected' as they just provide "symlinks" to the main python3 component, which provides the actual interpreter of the Python programming language.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Red Hat recommends upgrading to a fixed release of Python as soon as one is available. This vulnerability can be mitigated by rejecting links inside tarfiles that use relative references to the parent directory. The upstream advisory provides this example code:

'''

Avoid insecure segments in link names.

for member in tar.getmembers(): if not member.islnk(): continue if os.pardir in os.path.split(member.linkname): raise OSError("Tarfile with insecure segment ('..') in linkname")

Now safe to extract members with the data filter.

tar.extractall(filter="data") '''