CVE-2026-19672: tarfile extraction filter bypass allows creation of directories outside the 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.
Only empty directories are created outside the destination. 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.
Affected Software
Event History
Frequently Asked Questions
Which deployments are exposed to this issue?
Only POSIX platforms are affected. Windows is not affected because it collapses '..' path components before they reach the filesystem.
What must an attacker-controlled archive contain to trigger the behavior?
A member name must leave the extraction destination and then return to it, such as '../evil/../dest/sub/file'. To return, the name must include the final component of the destination directory.
Are extracted file contents written outside the intended destination?
No. Only empty intermediate directories can be created outside the destination; member contents are still extracted inside the destination.
What mitigation is available if patching cannot happen immediately?
Extract archives into a securely randomized destination directory. This prevents the required return-to-destination path from naming the destination directory's final component.