Medium [CVE-2026-19672] Python tarfile module: Directory traversal allows creation of empty directories outside extraction destination

The tarfile module's tar and data extraction filters created directories outside the destination for members whose name leaves the destination and returns to it, such as../evil/../dest/sub/file. The containment check used the resolved path, but intermediate directories were created from the name as given.

Member contents are still extracted inside it. To return to the destination the member's name must contain the destination directory's own final component, so extraction into a secure randomised directory is not affected.

This affects POSIX platforms only. On Windows,.. components are collapsed before the path reaches the filesystem, so the directories outside the destination are never created.

This vulnerability allows an attacker to create empty directories outside of the intended extraction destination on POSIX (Portable Operating System Interface) platforms. This occurs when processing a specially crafted archive containing member names that use directory traversal sequences (e.g., `../`) to leave and then re-enter the target directory.

While only empty directories are created outside the destination, this can lead to unintended file system modifications. Red Hat severity: Moderate — CVSS 5.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N).

Weakness: CWE-22. Affected Red Hat products: Red Hat Hardened Images.