CVE-2026-39243Public exploit

File disclosure and corruption via unvalidated hardlinks

Published Jul 9, 2026 · Updated Jul 9, 2026

Hardlink injection in decompress 4.2.1 and earlier allows attackers to read or corrupt same-filesystem files through a crafted archive. In index.js, the hardlink branch passes the archive-controlled x.linkname value directly to fs.link() without checking whether the target remains within the extraction directory. Exploitation requires an application or user to extract the archive; targets must be files on the same filesystem, and directories cannot be linked.

CVSS severity5.5
Medium
EPSS probability0.30%
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

Hardlink injection in decompress 4.2.1 and earlier allows attackers to read or corrupt same-filesystem files through a crafted archive. In index.js, the hardlink branch passes the archive-controlled x.linkname value directly to fs.link() without checking whether the target remains within the extraction directory. Exploitation requires an application or user to extract the archive; targets must be files on the same filesystem, and directories cannot be linked.

The record

CVE
CVE-2026-39243
Published
Jul 9, 2026
Updated
Jul 9, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-59, T1565.001, T1005
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 9, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 9, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.5CISA-ADPCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A: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 exploitPublished

Weakness, pattern, technique

CWE-59Improper Link Resolution Before File Access ('Link Following')
T1565.001Stored Data Manipulation
T1005Data from Local System

Public exploit references

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