HIGH CVSS 7.5
Published: 2026-02-25

CVE-2026-20128

cisco catalyst_sd-wan_manager Security Advisory (CVE-2026-20128)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-20128 impacting cisco catalyst_sd-wan_manager. Evaluated with CVSS Base Score of 7.5 (HIGH).

Original NVD Description

Source: NIST NVD
A vulnerability in the Data Collection Agent (DCA) feature of Cisco Catalyst SD-WAN Manager could allow an unauthenticated, remote attacker to gain DCA user privileges on an affected system. This vulnerability is due to the presence of a credential file for the DCA user on an affected system. An attacker could exploit this vulnerability by sending a crafted HTTP request and reading the file that contains the DCA password from that affected system. A successful exploit could allow the attacker to access another affected system and gain DCA user privileges. Note: Cisco Catalyst SD-WAN Manager releases 20.18 and later are not affected by this vulnerability.

📊 CVSS v3.1 Metric Breakdown

Attack Vector
Local (AV:L)
Requires local system execution permissions
Attack Complexity
High (AC:H)
Depends on race conditions or environment
Privileges Required
High (PR:H)
Administrative credentials required
User Interaction
None (UI:N)
Zero human interaction required
Scope
Changed (S:C)
Impacts components beyond caller authority
Confidentiality
High (C:H)
Total information disclosure
Integrity
High (I:H)
Total modification of target system
Availability
High (A:H)
Total denial of service or shutdown

🎯 Affected Versions Matrix

Affected Product cisco / catalyst_sd-wan_manager
Affected Versions *
Weakness Enumeration CWE-257

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-2026-20128 impacting cisco catalyst_sd-wan_manager.

⚡ Nuclei Detection Template (YAML) cve-2026-20128.yaml
id: cve-2026-20128

info:
  name: cisco catalyst_sd-wan_manager - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: high
  description: |
    Automated signature & scanner for CVE-2026-20128 affecting cisco catalyst_sd-wan_manager.
    Evaluation: A vulnerability in the Data Collection Agent (DCA) feature of Cisco Catalyst SD-WAN Manager could allow an unauthenticated, remote attacker to gain DC...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-20128
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H
    cvss-score: 7.5
    cve-id: CVE-2026-20128
    cwe-id: CWE-257
  tags: cve,cve-2026-20128,cisco,catalyst_sd-wan_manager,high

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "catalyst_sd-wan_manager"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-20128.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-20128
# Target: cisco catalyst_sd-wan_manager | 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-2026-20128 (cisco catalyst_sd-wan_manager)...")
    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 cisco catalyst_sd-wan_manager 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-2026-20128.sh
# Recommended Remediation & Patching Commands for CVE-2026-20128
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install catalyst_sd-wan_manager 2>/dev/null || \
sudo dnf upgrade catalyst_sd-wan_manager 2>/dev/null || \
sudo yum update catalyst_sd-wan_manager

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

# 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-2026-20128 in cisco catalyst_sd-wan_manager?

Review vendor-specific security notices and update cisco catalyst_sd-wan_manager 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-2026-20128?

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-2026-20128?

CVE-2026-20128 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-2026-20128
Weakness CWE-257
Vendor cisco
Product catalyst_sd-wan_manager
Published 2026-02-25
Vector CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H