What’s Vulnerable › Vulnerabilities

CVE-2026-11972: tarfile opened in streaming mode mishandles EOF

• Severity: high (CVSS 8.2 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-23 · updated 2026-10-25
• Weakness: CWE-252

Description

When using the "tarfile" module with a file opened in "streaming mode" (mode="r|") the tarfile module did not properly handle EOF, making archive parsing take exponentially longer.

Affected products

• Python: before 3.10.21; from 3.11.0 before 3.11.16; from 3.12.0 before 3.12.14; from 3.13.0 before 3.13.15; from 3.14.0 before 3.14.7; from 3.15.0a1 before 3.15.0b4 — fixed in 3.10.21, 3.11.16, 3.12.14, 3.13.15, 3.14.7, 3.15.0b4

How to fix

Upgrade to a fixed version: Python 3.10.21, 3.11.16, 3.12.14, 3.13.15. Check the vendor advisory for mitigations.

References

• https://github.com/python/cpython/commit/3f031d431f80668e14f3bc066bbf4369cd9281b9
• https://github.com/python/cpython/commit/4ce6bf7c8aa7725828a38981c306f214c1f29365
• https://github.com/python/cpython/commit/7f0dc59c9a70f8f3b4da33d7c4a2ba552a7acc21
• https://github.com/python/cpython/commit/e86666c9dd256d52d0fbef6feb1ea4a51768fdec
• https://github.com/python/cpython/commit/eb63c0f94dfcbea7fda8eab6213818e134d67192
• https://github.com/python/cpython/commit/f50bf13566189c8d0ce5a814f33eff3d89951896
• https://github.com/python/cpython/commit/f5e2776ff0383a902c12acf2b703e7e951fc8438
• https://github.com/python/cpython/issues/151981
• https://github.com/python/cpython/pull/151982
• https://mail.python.org/archives/list/security-announce@python.org/thread/AXPSKKTSRKXTTJULW3XSIC74WZNAAPPB/

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