MEDIUM CVSS 5.5
Published: 2026-07-09

CVE-2026-39243

decompress_project decompress Security Advisory (CVE-2026-39243)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-39243 impacting decompress_project decompress. Evaluated with CVSS Base Score of 5.5 (MEDIUM).

Original NVD Description

Source: NIST NVD
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.

📊 CVSS v3.1 Metric Breakdown

Attack Vector
Local (AV:L)
Requires local system execution permissions
Attack Complexity
Low (AC:L)
No specialized conditions required
Privileges Required
None (PR:N)
Unauthenticated execution
User Interaction
Required (UI:R)
User must click or open resource
Scope
Unchanged (S:U)
Confined to same security context
Confidentiality
High (C:H)
Total information disclosure
Integrity
None (I:N)
No system modification impact
Availability
None (A:N)
No system availability impact

🎯 Affected Versions Matrix

Affected Product decompress_project / decompress
Affected Versions *
Weakness Enumeration CWE-59

Security Research Arsenal: Nuclei Detection Template & PoC Exploit Probe

High-Intent Research Tool

Ready-to-use security scanner signatures, active verification probe skeletons, and remediation playbooks for CVE-2026-39243 impacting decompress_project decompress.

⚡ Nuclei Detection Template (YAML) cve-2026-39243.yaml
id: cve-2026-39243

info:
  name: decompress_project decompress - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: medium
  description: |
    Automated signature & scanner for CVE-2026-39243 affecting decompress_project decompress.
    Evaluation: decompress before 4.2.2 allows arbitrary hardlink creation during archive extraction, enabling file read disclosure and file corruption. When processi...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-39243
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
    cvss-score: 5.5
    cve-id: CVE-2026-39243
    cwe-id: CWE-59
  tags: cve,cve-2026-39243,decompress_project,decompress,medium

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "decompress"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-39243.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-39243
# Target: decompress_project decompress | CVSS: 5.5 (MEDIUM)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-39243 (decompress_project decompress)...")
    headers = {
        "User-Agent": "CyberVault-Audit-Scanner/2.0",
        "Accept": "*/*"
    }
    try:
        r = requests.get(f"{target_url.rstrip('/')}/", headers=headers, timeout=8, verify=False)
        print(f"[+] Server Response: HTTP {r.status_code} | Server Banner: {r.headers.get('Server', 'Unknown')}")
        if r.status_code < 500:
            print(f"[!] Target reachable. Verify version against decompress_project decompress scope (*).")
        return True
    except Exception as e:
        print(f"[-] Connection Error: {e}")
        return False

if __name__ == '__main__':
    url = sys.argv[1] if len(sys.argv) > 1 else "http://localhost:8080"
    verify_vulnerability(url)
🛡️ Quick Patch & Remediation Script (Bash) patch_cve-2026-39243.sh
# Recommended Remediation & Patching Commands for CVE-2026-39243
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install decompress 2>/dev/null || \
sudo dnf upgrade decompress 2>/dev/null || \
sudo yum update decompress

# 2. Inspect installed package versions for vulnerable scope:
dpkg -l | grep -i decompress 2>/dev/null || rpm -qa | grep -i decompress

# 3. Docker container & image vulnerability scan:
docker scan $(docker ps -q) 2>/dev/null || echo "Verify upstream base images in Dockerfile."

🛡️ Remediation & Security Action

  • Authoritative Guidance: Follow distribution-specific vendor security notices. Advisory status and package patches vary by distribution release.
  • Verification: Inspect installed binary packages and package manager versions for affected component releases.
  • Upstream Status: Upgrade to verified non-backdoored upstream versions or roll back to known-clean stable releases.
⚠️ Disclaimer: Follow vendor-specific advisories for your operating system. CyberVault does not fabricate unsupported remediation scripts.

🔗 Verified Technical References

❓ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2026-39243 in decompress_project decompress?

Review vendor-specific security notices and update decompress_project decompress packages to the latest patched release immediately. If immediate upgrading is restricted by change windows, isolate affected network ports and enforce least-privilege access boundaries.

Is there an active exploit or public PoC for CVE-2026-39243?

No weaponized public exploit has been confirmed in public threat streams yet. Continuous surveillance is active across GitHub and security feeds.

What is the CVSS 3.1 severity rating and impact for CVE-2026-39243?

CVE-2026-39243 is classified with a CVSS 3.1 Base Score of 5.5 (MEDIUM). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
5.5
MEDIUM SEVERITY
CVE ID CVE-2026-39243
Weakness CWE-59
Vendor decompress_project
Product decompress
Published 2026-07-09
Vector CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N