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Public proof of conceptFix available

CVE-2026-39243

A public proof of concept exists; no exploitation attested.

  • Published2026-07-09
  • WeaknessCWE-59

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

decompress before 4.2.2 allows arbitrary hardlink creation during archive extraction, enabling file read disclosure and file corruption. When processing hardlink entries (type === 'link'), the x.linkname field from the archive is passed directly to fs.link() without validation (index.js line 113). An attacker can craft an archive with a hardlink entry whose linkname is an absolute path to any file on the same filesystem. This creates a hardlink inside the extraction directory that shares the same inode as the target file, enabling both reading and overwriting the original file's content. Hardlinks are limited to files on the same filesystem and cannot target directories.

Timeline

dates in UTC
  1. 2026-07-0922:17CVE publishedNVD

Versions per branch

OSV · NVD
decompress
BranchAffectedFixed in
4.2≤ 4.2.1no fix published
Decompress project decompress
BranchAffectedFixed in
4.2≤ 4.2.1no fix published

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • cube-1.7MinimOSall versions · fixed in 1.7.22-r0
  • decompressTuxCare:npmfrom 4.2.1-tuxcare.0 · fixed in 4.2.1-tuxcare.1
  • dotnet-hostfxr-8.0Red Hat:hummingbird:1all versions · fixed in 0:8.0.28-1.1.hum1and 7 other packages
  • dotnet-sdk-8.0Red Hat:hummingbird:1all versions · fixed in 0:8.0.128-1.1.hum1and 4 other packages
  • ghost-cliMinimOSall versions · fixed in 1.32.0-r0
  • mcp-mongodbMinimOSall versions · fixed in 3.1.0-r0

Vendor advisories

  • RHSA-2026:37577 Red Hat Product Security9 products fixed

    Red Hat Security Advisory: Red Hat Hardened Images RPMs Security Update

Full record on NVD

Fix

  1. Vendor fix Red Hat Product Security RHSA-2026:37577 · 9 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
  2. Workaround from the vendor Red Hat Product Security RHSA-2026:37577 · 25 productsTo mitigate this issue, avoid extracting archives from untrusted or unknown sources. When processing archives from potentially untrusted origins, consider using a sandboxed environment to limit the impact of any malicious content.

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
Published
2026-07-09
Last Modified
2026-07-13
NVD status
Analyzed
GitHub Advisory
GHSA-jwp9-9v96-94mx

Frequently asked questions

What is CVE-2026-39243?

decompress before 4.2.2 allows arbitrary hardlink creation during archive extraction, enabling file read disclosure and file corruption. When processing hardlink entries (type === 'link'), the x.linkname field from the archive is passed directly to fs.link() without validation (index.js line 113). An attacker can craft an archive with a hardlink entry whose linkname is an absolute path to any file on the same filesystem. This creates a hardlink inside the extraction directory that shares the same inode as the target file, enabling both reading and overwriting the original file's content. Hardlinks are limited to files on the same filesystem and cannot target directories.

Is CVE-2026-39243 actively exploited?

A proof-of-concept exploit exists for CVE-2026-39243, but active exploitation has not been confirmed at this time.

What is the CVSS score for CVE-2026-39243?

CVE-2026-39243 has a CVSS v3 base score of 5.5 (MEDIUM severity), with vector string CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N.

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Sources for this record