CVE-2026-4360Network attack vector

File ownership manipulation via unfiltered hardlink fallback

Published Jun 30, 2026 · Updated Jun 30, 2026

Improper permission preservation in CPython's tarfile module allows attackers to write extracted files with unintended ownership. TarFile.extract's missing-target hardlink fallback calls _extract_one without forwarding filter_function, so archived uid and gid values bypass the data filter. Exploitation requires an untrusted archive and a privileged extraction process able to apply ownership, allowing attacker-selected file owners or groups.

CVSS severity2.0
Low
EPSS probability0.28%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Improper permission preservation in CPython's tarfile module allows attackers to write extracted files with unintended ownership. TarFile.extract's missing-target hardlink fallback calls _extract_one without forwarding filter_function, so archived uid and gid values bypass the data filter. Exploitation requires an untrusted archive and a privileged extraction process able to apply ownership, allowing attacker-selected file owners or groups.

The record

CVE
CVE-2026-4360
Published
Jun 30, 2026
Updated
Jun 30, 2026
Vendor
Python Software Foundation
Product
CPython
Classifications
CWE-281, T1204.002
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Jun 30, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 30, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <3.15.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

Python Software Foundation · CPythonversion=0 <3.15.0

Published CVSS scores

5.3NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
2.0Python Software FoundationCVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-281Improper Preservation of Permissions
T1204.002Malicious File

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo