CVE-2025-20340
📋 TL;DR
This vulnerability allows an unauthenticated attacker on the same network segment to send excessive ARP traffic to the management interface of Cisco IOS XR devices, causing broadcast storms that can degrade performance or cause complete system unresponsiveness. It affects Cisco IOS XR Software users with vulnerable versions exposed to adjacent network traffic.
💻 Affected Systems
- Cisco IOS XR Software
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Complete device unresponsiveness leading to network outage, loss of management connectivity, and potential cascading failures in dependent systems.
Likely Case
Degraded device performance, intermittent management connectivity loss, and service disruption requiring manual intervention.
If Mitigated
Minimal impact with proper network segmentation and traffic filtering in place.
🎯 Exploit Status
Exploitation requires sustained high-rate ARP traffic to management interface from adjacent network.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Cisco advisory for specific fixed versions
Vendor Advisory: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-arp-storm-EjUU55yM
Restart Required: Yes
Instructions:
1. Review Cisco advisory for affected versions. 2. Download and apply appropriate software update. 3. Reboot device as required. 4. Verify fix implementation.
🔧 Temporary Workarounds
Network Segmentation
allIsolate management interface on separate VLAN or network segment to limit adjacent attacker access.
Traffic Rate Limiting
cisco-ios-xrImplement ARP traffic rate limiting on management interface using QoS policies.
policy-map ARP-LIMIT
class class-default
police rate <value>
🧯 If You Can't Patch
- Implement strict network access controls to limit which devices can communicate with management interfaces.
- Deploy network monitoring to detect ARP storm patterns and alert on abnormal traffic volumes.
🔍 How to Verify
Check if Vulnerable:
Check Cisco advisory for affected versions and compare with 'show version' output.Check Version:
show version | include Cisco IOS XR SoftwareVerify Fix Applied:
Verify installed software version matches or exceeds fixed version listed in Cisco advisory.📡 Detection & Monitoring
Log Indicators:
- High ARP packet counts in interface statistics
- System log messages indicating performance degradation
- Management connectivity loss events
Network Indicators:
- Unusually high ARP broadcast traffic to management interfaces
- Network performance degradation coinciding with ARP traffic spikes
SIEM Query:
source="network_device" (event_type="interface_counter" AND packet_type="arp" AND rate>threshold) OR (event_type="system_performance" AND metric="cpu_usage" AND value>high_threshold)