HIGH CVSS 8.6
Published: 2026-04-09

CVE-2026-39983

patrickjuchli basic-ftp Security Advisory (CVE-2026-39983)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-39983 impacting patrickjuchli basic-ftp. Evaluated with CVSS Base Score of 8.6 (HIGH).

Original NVD Description

Source: NIST NVD
basic-ftp is an FTP client for Node.js. Prior to 5.2.1, basic-ftp allows FTP command injection via CRLF sequences (\r\n) in file path parameters passed to high-level path APIs such as cd(), remove(), rename(), uploadFrom(), downloadTo(), list(), and removeDir(). The library's protectWhitespace() helper only handles leading spaces and returns other paths unchanged, while FtpContext.send() writes the resulting command string directly to the control socket with \r\n appended. This lets attacker-controlled path strings split one intended FTP command into multiple commands. This vulnerability is fixed in 5.2.1.

📊 CVSS v3.1 Metric Breakdown

Attack Vector
Network (AV:N)
Exploitable remotely across internet boundaries
Attack Complexity
Low (AC:L)
No specialized conditions required
Privileges Required
None (PR:N)
Unauthenticated execution
User Interaction
None (UI:N)
Zero human interaction required
Scope
Unchanged (S:U)
Confined to same security context
Confidentiality
Low (C:L)
Partial information leakage
Integrity
High (I:H)
Total modification of target system
Availability
Low (A:L)
Partial service performance degradation

🎯 Affected Versions Matrix

Affected Product patrickjuchli / basic-ftp
Affected Versions *
Weakness Enumeration CWE-93

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-2026-39983 impacting patrickjuchli basic-ftp.

⚡ Nuclei Detection Template (YAML) cve-2026-39983.yaml
id: cve-2026-39983

info:
  name: patrickjuchli basic-ftp - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: high
  description: |
    Automated signature & scanner for CVE-2026-39983 affecting patrickjuchli basic-ftp.
    Evaluation: basic-ftp is an FTP client for Node.js. Prior to 5.2.1, basic-ftp allows FTP command injection via CRLF sequences (\r\n) in file path parameters passe...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-39983
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:L
    cvss-score: 8.6
    cve-id: CVE-2026-39983
    cwe-id: CWE-93
  tags: cve,cve-2026-39983,patrickjuchli,basic-ftp,high

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "basic-ftp"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-39983.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-39983
# Target: patrickjuchli basic-ftp | CVSS: 8.6 (HIGH)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-39983 (patrickjuchli basic-ftp)...")
    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 patrickjuchli basic-ftp 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-2026-39983.sh
# Recommended Remediation & Patching Commands for CVE-2026-39983
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install basic-ftp 2>/dev/null || \
sudo dnf upgrade basic-ftp 2>/dev/null || \
sudo yum update basic-ftp

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

# 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.

❓ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2026-39983 in patrickjuchli basic-ftp?

Review vendor-specific security notices and update patrickjuchli basic-ftp 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-2026-39983?

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-2026-39983?

CVE-2026-39983 is classified with a CVSS 3.1 Base Score of 8.6 (HIGH). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
8.6
HIGH SEVERITY
CVE ID CVE-2026-39983
Weakness CWE-93
Vendor patrickjuchli
Product basic-ftp
Published 2026-04-09
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:L