HighCVE-2026-11940

tarfile extraction filter bypass allows escaping the destination directory (CVE-2026-11940)

Published 23.06.2026Last modified 26.10.2026Sources: Red Hat, SUSE, BSI, CVE.org, OSV

What is affected, what to do

A flaw was found in the `tarfile.extractall()` function within Python. A remote attacker could exploit this vulnerability by providing a specially crafted archive.

Update Python Software Foundation CPython to version 3.10.21, Python Software Foundation CPython to version 3.11.16, Python Software Foundation CPython to version 3.12.14.

Affected: Python Software Foundation CPython lt *..3.10.21
Python Software Foundation CPython lt 3.11.0..3.11.16
Python Software Foundation CPython lt 3.12.0..3.12.14
Python Software Foundation CPython lt 3.13.0..3.13.15
Python Software Foundation CPython lt 3.14.0..3.14.7
Python Software Foundation CPython lt 3.15.0a1..3.15.0b4
Fixed in: Python Software Foundation CPython 3.10.21
Python Software Foundation CPython 3.11.16
Python Software Foundation CPython 3.12.14
Python Software Foundation CPython 3.13.15
Python Software Foundation CPython 3.14.7
Python Software Foundation CPython 3.15.0b4

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Metrics

7.8

Priority

XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

Source: NVD, CVSS v4

7.8

CVSS v4

Severity High on the scale from 0 to 10.

Source: Red Hat, SUSE, BSI, CVE.org, OSV

0.8 %

EPSS score

Low — model estimates < 1% exploitation likelihood.

Source: FIRST EPSS, percentile 54.8

Show all metrics

Severity: High
Priority (0–325) The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first? Read in glossary: 82.47 Methodology
Exploit maturity An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack. Read in glossary: no public PoC known
XIEM Effective CVSS XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command. Read in glossary: 7.8 Methodology
CVSS v4 CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions. Read in glossary: 7.8
EPSS score The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“. Read in glossary: 0.8 %; Low — model estimates < 1% exploitation likelihood.
EPSS percentile The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking. Read in glossary: 54.8; High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
KEV status The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching. Read in glossary: —
Published: 23.06.2026
CWE CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect. Read in glossary: CWE-22, CWE-59

Detection rules

No NEOSEC detection rule is available for this vulnerability yet.

Classification under NIS2 and CRA

Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

NIS2 NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management. Read in glossary: High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
CRA The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates. Read in glossary: From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001 ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security. Read in glossary: Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

Description

A flaw was found in the `tarfile.extractall()` function within Python. A remote attacker could exploit this vulnerability by providing a specially crafted archive. This archive could bypass security filters by using a hardlink that references a symlink, allowing the symlink to be recreated outside the intended destination directory. This could lead to out-of-destination file reads or writes, potentially resulting in information disclosure or arbitrary file modification.

Source: redhat_csaf, suse_csaf, BSI WID Portal, BSI CSAF, NVD (NIST), OSV (Open Source Vulnerabilities), cvelistv5, CVE.org (MITRE)

Affected products

The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

Affected products
		Affected versions	Fixed in
Python Software Foundation	CPython	`3.12.0 – < 3.12.14` `3.11.0 – < 3.11.16` `3.13.0 – < 3.13.15` `< 3.10.21` `3.15.0a1 – < 3.15.0b4` `3.14.0 – < 3.14.7`	`3.12.14` `3.11.16` `3.13.15` `3.10.21` `3.15.0b4` `3.14.7`
IBM	QRadar SIEM	`< 7.6.0.3` `<7.5.0 UP16 IF01`	`7.6.0.3` —
Open Source	Python CPython	`< 3.15.0`	`3.15.0`

Vendors and products

Weakness classes (CWE)

CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Base
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.
Entry at MITRE CWE-22
CWE-59Improper Link Resolution Before File Access ('Link Following')
Base
The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.
Entry at MITRE CWE-59

References & sources

github.compython/cpython/pull/151559web, Patch
mail.python.orgarchives/list/security-announce@python.org/thread/LD6QIISNQFQYO…advisory, Vendor advisory
github.compython/cpython/issues/151558report, Issue tracking
github.compython/cpython/commit/27dd970bf6b17ebca7c8ed486a40ab043ed7af8ffix, Patch
github.compython/cpython/commit/672825e2f36a57e173959b0d9d409d4560dab8dffix, Patch
github.compython/cpython/commit/771d12dda5140313db0ac550292987975651bbdefix, Patch
github.compython/cpython/commit/79c06bd5c6afa3c440d50faf7ee1b147c8832b4cfix, Patch
github.compython/cpython/commit/be13e86f6b9788a6f4d0419dffef72cbae5865c9fix, Patch
github.compython/cpython/commit/e5fdbd8d5aa923bd9111b112ea73bd6ec7c47877Patch
github.compython/cpython/commit/0f852b3f07dd8e71e40326a51c02afbf16a42cc5fix, Patch
NVD (NIST)vuln/detail/CVE-2026-11940web

Changes to this CVE

Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

11.08.2026Record modifiedpython.org
New references:
- https://github.com/python/cpython/commit/0f852b3f07dd8e71e40326a51c02afbf16a42cc5
Show the original change
Individual changes of this event as published by NVD
Type Action Before After
Reference added
—
https://github.com/python/cpython/commit/0f852b3f07dd8e71e40326a51c02afbf16a42cc5
Source identifier: cna@python.org
05.08.2026Record modifiedpython.org
1 individual change: Affected versions (publisher)
Show the original change
Individual changes of this event as published by NVD
Type Action Before After
Affected versions (publisher) changed
CPython
CPython
Source identifier: cna@python.org

Individual changes of this event as published by NVD
Type	Action	Before	After
Reference	added	—	https://github.com/python/cpython/commit/0f852b3f07dd8e71e40326a51c02afbf16a42cc5

Individual changes of this event as published by NVD
Type	Action	Before	After
Affected versions (publisher)	changed	CPython	CPython

23.06.2026Record modifiedpython.org

New references:

Show 5 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Reference	added	—	https://github.com/python/cpython/commit/27dd970bf6b17ebca7c8ed486a40ab043ed7af8f
Reference	added	—	https://github.com/python/cpython/commit/672825e2f36a57e173959b0d9d409d4560dab8df
Reference	added	—	https://github.com/python/cpython/commit/771d12dda5140313db0ac550292987975651bbde
Reference	added	—	https://github.com/python/cpython/commit/79c06bd5c6afa3c440d50faf7ee1b147c8832b4c
Affected versions (publisher)	changed	CPython	CPython

Source identifier: cna@python.org

23.06.2026Record modifiedCISA ADP

CISA assessment (SSVC): exploitation: none known, automatable: yes

Show the original change

Individual changes of this event as published by NVD
Type	Action	Before	After
SSVC assessment	added	—	{"id":"CVE-2026-11940","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"partial"}],"version":"2.0.3","timestamp":"2026-06-23T17:57:25.652265Z"}

Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

23.06.2026Receivedpython.org

CVSS V4.0: AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N

Weakness type: CWE-22, CWE-59

Description added or changed

New references:

Show 8 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Affected versions (publisher)	added	—	CPython
Description	added	—	tarfile.extractall() with the 'data' or 'tar' filter could be bypassed by a crafted archive where a hardlink references a symlink stored at a deeper name than the hardlink itself. The extraction fallback validated the symlink at it's archived location but recreated it at the hardlink's shallower path, letting a relative target the filter judged contained escape the destination directory. This allowed a malicious tar archive to create a symlink pointing outside the destination, enabling out-of-destination file reads or writes. This was an incomplete fix of CVE-2025-4330.
CVSS	added	—	AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Weakness type (CWE)	added	—	CWE-22
Weakness type (CWE)	added	—	CWE-59
Reference	added	—	https://github.com/python/cpython/issues/151558
Reference	added	—	https://github.com/python/cpython/pull/151559
Reference	added	—	https://mail.python.org/archives/list/security-announce@python.org/thread/LD6QIISNQFQYOIEPJNEUIPV7S3V76FZH/

Source identifier: cna@python.org

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<a href="https://intel.neosec.eu/en/cve/CVE-2026-11940"><img src="https://intel.neosec.eu/badge/cve/CVE-2026-11940.svg?lang=en" alt="CVE-2026-11940 – NEOSEC Intel" height="20"></a>