HIGH CVSS 7.5
Published: 2017-12-06

CVE-2017-17439

debian debian_linux Security Advisory (CVE-2017-17439)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2017-17439 impacting debian debian_linux. Evaluated with CVSS Base Score of 7.5 (HIGH).

Original NVD Description

Source: NIST NVD
In Heimdal through 7.4, remote unauthenticated attackers are able to crash the KDC by sending a crafted UDP packet containing empty data fields for client name or realm. The parser would unconditionally dereference NULL pointers in that case, leading to a segmentation fault. This is related to the _kdc_as_rep function in kdc/kerberos5.c and the der_length_visible_string function in lib/asn1/der_length.c.

📊 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
None (C:N)
No data confidentiality impact
Integrity
None (I:N)
No system modification impact
Availability
High (A:H)
Total denial of service or shutdown

🎯 Affected Versions Matrix

Affected Product debian / debian_linux
Affected Versions 9.0
Weakness Enumeration CWE-476

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-2017-17439 impacting debian debian_linux.

⚡ Nuclei Detection Template (YAML) cve-2017-17439.yaml
id: cve-2017-17439

info:
  name: debian debian_linux - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: high
  description: |
    Automated signature & scanner for CVE-2017-17439 affecting debian debian_linux.
    Evaluation: In Heimdal through 7.4, remote unauthenticated attackers are able to crash the KDC by sending a crafted UDP packet containing empty data fields for cl...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2017-17439
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
    cvss-score: 7.5
    cve-id: CVE-2017-17439
    cwe-id: CWE-476
  tags: cve,cve-2017-17439,debian,debian_linux,high

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "debian_linux"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2017-17439.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2017-17439
# Target: debian debian_linux | CVSS: 7.5 (HIGH)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2017-17439 (debian debian_linux)...")
    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 debian debian_linux scope (9.0).")
        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-2017-17439.sh
# Recommended Remediation & Patching Commands for CVE-2017-17439
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install debian_linux 2>/dev/null || \
sudo dnf upgrade debian_linux 2>/dev/null || \
sudo yum update debian_linux

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

# 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-2017-17439 in debian debian_linux?

Review vendor-specific security notices and update debian debian_linux 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-2017-17439?

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-2017-17439?

CVE-2017-17439 is classified with a CVSS 3.1 Base Score of 7.5 (HIGH). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
7.5
HIGH SEVERITY
CVE ID CVE-2017-17439
Weakness CWE-476
Vendor debian
Product debian_linux
Published 2017-12-06
Vector CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H