HIGH CVSS 8.6
Published: 2025-03-12

CVE-2025-20146

cisco ios_xr Security Advisory (CVE-2025-20146)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2025-20146 impacting cisco ios_xr. Evaluated with CVSS Base Score of 8.6 (HIGH).

Original NVD Description

Source: NIST NVD
A vulnerability in the Layer 3 multicast feature of Cisco IOS XR Software for Cisco ASR 9000 Series Aggregation Services Routers, ASR 9902 Compact High-Performance Routers, and ASR 9903 Compact High-Performance Routers could allow an unauthenticated, remote attacker to cause a line card to reset, resulting in a denial of service (DoS) condition. This vulnerability is due to the incorrect handling of malformed IPv4 multicast packets that are received on line cards where the interface has either an IPv4 access control list (ACL) or a QoS policy applied. An attacker could exploit this vulnerability by sending crafted IPv4 multicast packets through an affected device. A successful exploit could allow the attacker to cause line card exceptions or a hard reset. Traffic over that line card would be lost while the line card reloads.

📊 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
Changed (S:C)
Impacts components beyond caller authority
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 cisco / ios_xr
Affected Versions 7.9.21
Weakness Enumeration CWE-20

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-2025-20146 impacting cisco ios_xr.

⚡ Nuclei Detection Template (YAML) cve-2025-20146.yaml
id: cve-2025-20146

info:
  name: cisco ios_xr - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: high
  description: |
    Automated signature & scanner for CVE-2025-20146 affecting cisco ios_xr.
    Evaluation: A vulnerability in the Layer 3 multicast feature of Cisco IOS XR Software for Cisco ASR 9000 Series Aggregation Services Routers, ASR 9902 Compact Hig...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2025-20146
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
    cvss-score: 8.6
    cve-id: CVE-2025-20146
    cwe-id: CWE-20
  tags: cve,cve-2025-20146,cisco,ios_xr,high

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "ios_xr"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2025-20146.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2025-20146
# Target: cisco ios_xr | 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-2025-20146 (cisco ios_xr)...")
    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 ios_xr scope (7.9.21).")
        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-2025-20146.sh
# Recommended Remediation & Patching Commands for CVE-2025-20146
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install ios_xr 2>/dev/null || \
sudo dnf upgrade ios_xr 2>/dev/null || \
sudo yum update ios_xr

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

# 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-2025-20146 in cisco ios_xr?

Review vendor-specific security notices and update cisco ios_xr 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-2025-20146?

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-2025-20146?

CVE-2025-20146 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-2025-20146
Weakness CWE-20
Vendor cisco
Product ios_xr
Published 2025-03-12
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H