CVE-2026-66484

External file linkage via unsanitized hard-link targets

Published Aug 10, 2026 · Updated Aug 10, 2026

Path traversal in GNU Project cpio 2.15 and earlier allows attackers to create hard links outside the extraction directory via a crafted tar archive. In copy-in mode, --no-absolute-filenames normalizes the member name but passes the tar hard-link target to link_to_name without equivalent sanitization. Exploitation requires extraction with that option and can link an archive-controlled path to an existing file accessible to the cpio process.

CVSS severity4.6
Medium
EPSS probability0.16%
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

Path traversal in GNU Project cpio 2.15 and earlier allows attackers to create hard links outside the extraction directory via a crafted tar archive. In copy-in mode, --no-absolute-filenames normalizes the member name but passes the tar hard-link target to link_to_name without equivalent sanitization. Exploitation requires extraction with that option and can link an archive-controlled path to an existing file accessible to the cpio process.

The record

CVE
CVE-2026-66484
Published
Aug 10, 2026
Updated
Aug 10, 2026
Vendor
The GnuPG Project
Product
GNU cpio
Classifications
CWE-22, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 10, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 10, 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 <=2.15

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

The GnuPG Project · GNU cpioversion=0 <=2.15

Published CVSS scores

3.3Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
4.6UbuntuCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:L/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
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